The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools
Old March 23, 2012, 10:15 PM   #26
F. Guffey
Senior Member
 
Join Date: July 18, 2008
Posts: 2,738
Wyordeman, you ask:

“Is there a way to figure COAL from the ogive without the comparator? I ordered one today, but I wanted to shoot this test this weekend. Damn the luck?”

The answer is yes, (another way to figure maximum COL) then you ordered one today? That is fast.

F. Guffey
F. Guffey is online now  
Old March 23, 2012, 10:27 PM   #27
mrawesome22
Senior Member
 
Join Date: November 9, 2005
Location: Ohio, Appalachia's foothills.
Posts: 3,779
Just thought I would add, if you aren't using brass that has been meticulously prepped and sorted and checked for runout, all this oal business could be for naught.

Rounds that are not concentric with the same internal volume and/or have a sloppy fit in the chamber will be all over the paper no matter how great the powder charge or how far they are off the rifling.
mrawesome22 is offline  
Old March 24, 2012, 10:33 AM   #28
F. Guffey
Senior Member
 
Join Date: July 18, 2008
Posts: 2,738
No matter what you do?

If I do not have the luxury of disagreeing I do it anyhow. L have two rifles, different manufacture, same chamber, same ammo, one groups like a shotgun, the other makes my reloading look good, I have one rifle that corrects all the ills of bad ammo. A builder of bench rest type rifles called and said he needed help, his necks before firing measured .335” after firing the neck measured .345”, my question, How do they shoot? answer, “One hole groups”. He had 500 fired cases, measuring all 500 would have been doable, but he said he measured. It is/was not for me to ask him just how much better can a one hole group can get, he wanted less neck expansion when the case released the bullet, now he can start with a neck that measures .341” and expands to .345, with regards to helping him, I thought I would be finished in two hours, in two hours “WE” had two cases ready to be sized to the chamber.

Then there is the mail order/Sears type 03 Remington before A3 with new or reloads, the groups move but never spread, no scope. I purchased that one while at a gun show called Big Town in Mesquite, TX, I took the owner to a bank to get the money, I lined up with a drive through lane, and he left, after calming him down he explained driving through a bank with a pick up full of rifles propped between the floor and seat would draw suspicion, and I explained to him, “NO, this is my bank”, I decided to drive through the ATM lane.


F. Guffey
F. Guffey is online now  
Old March 24, 2012, 02:24 PM   #29
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Unclenick says:
Quote:
So, let’s make an example. You load a .308 in a Winchester case, with the 175 grain MatchKing jammed 0.010” into the lands and find 41.4 grains of IMR4064 gives you best accuracy at a velocity of 2560 fps. You next seat a bullet 0.160” deeper, and find you now need 42.8 grains of 4064 to get to 2560 fps, matching the velocity of the first load. The difference is 1.5 grains. You multiply 1.5 grains by 1.4, giving you 2.1 grains, and add that to 41.4 grains. You now have 43.5 grains. This will be a little faster than the original velocity, but it should be about right to produce the same barrel time as the original load, so it should already be pretty well tuned.
I wouldn't bet on barrel time being the same for different charge weights of the same powder under the same bullet with the same neck tension. Expecially when you also state:
Quote:
But you still have another issue, and that is that as the pressure drops the velocity drops and the barrel time increases, and that can move you off a sweet spot for powder charge or move you onto one.
It all sounds contradictory to me. Wouldn't barrel time decrease with higher muzzle velocity?

What do you mean by a "sweet spot?" Something with muzzle velocity or barrel whip?
Bart B. is offline  
Old March 24, 2012, 04:41 PM   #30
Gunplummer
Senior Member
 
Join Date: March 11, 2010
Location: South East Pa.
Posts: 1,474
This whole thread is about "Feel good" extra work. I remember a '17 Enfield that after resizeing the brass it had gained about an average of .020-.025 in length. That is because military chambers are different. At 100 yards it shot great with factory ammo. I did an 8x57 barrel for a guy and he wanted it built to the dies he had. He fired off half a box of the brand of brass he was using, resized and trimmed all to length. I took measurements off the brass, and will admit there is a lot of "Feel" involved when you do this. I did the chamber, we fired off the reloaded half a box of brass that was sized and trimmed, resized it and started measuring. Not one case was more than .001 longer than the original trimmed size. I doubt neck sizing is that close, and there are issues with that I won't go into here. It shot O.K. at 100 yards but not great. This Guy liked to play and tried all kinds of recipes and it never was a tack driver. A lot of the reloading advice is nonsense because the gun or barrel is not good enough to take advantage of it anyway.
Gunplummer is offline  
Old March 24, 2012, 04:55 PM   #31
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,314
Bart,

Not contradictory, just not intuitive because its not linear, but it's how the physics of the beast work out. Velocity depends on the average pressure at the bullet base during its whole trip down the tube. You can get to the same average by combining a higher peak with a lower muzzle pressure or vice versa, giving you two different pressure profiles that produce the same muzzle velocity. The first accelerates the bullet more early in its trip, while the second does more of the accelerating later in the trip. The first profile thus has the bullet traversing the second half of the barrel in a shorter time because it gets there already going faster than the first. That's why it produces a shorter barrel time even though the muzzle velocity is the same.

Usually that first and second pressure profile is produced by fast and slow powders, respectively. But when you make a change in seating depth that requires more powder to reach the same velocity, then you are using a lower peak pressure value that makes the powder burn more slowly, and thus acting like a slower powder would, and garnering a longer barrel time for the same reason.

As to the the sweet spot in barrel time, yes, that's muzzle displacement timing. The thinner and more whippy the barrel, the more it matters. You can see Varmint Al's FEA animations to see the whip initiated and to learn the frequencies (roughly third harmonic) and rates of displacement. He's also got some nice animations of all the minor modes.

That said, there are a lot of guns for which simply matching velocity may be close enough. A lot of the barrel time sweet spots are several tens of microseconds wide, corresponding to up to a couple of inches of barrel length difference. That's because the bullets are going so fast that near the muzzle that it takes a lot of barrel length to make a big difference in barrel time). The formula I gave just gets you closer to staying at one barrel time that has already worked out for you.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member

Last edited by Unclenick; March 25, 2012 at 03:51 PM. Reason: corrected milliseconds to microseconds
Unclenick is offline  
Old March 24, 2012, 05:33 PM   #32
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Unclenick, you mentioned:
Quote:
A lot of the barrel time sweet spots are several tens of milliseconds wide. . .
My bad. I thought microseconds and typed milliseconds. I'll go back and fix it. Figure a bullet going 2500 fps will have 33μS/inch of travel. A load that stays accurate for a ±1% of powder charge in a .308 (about ±0.4 grains; not uncommon to find) will run just about ±32μS according to QuickLOAD, so almost a 2" span of barrel length. This explains why, in a post you had in another thread, the Garand with its muzzle funneled back 3/4" might not show any loss of accuracy timing with a good load tuned to a full length of rifling.

If you look at Varmint Al's animated FEA of a rifle firing you'll see his muzzle doesn't complete any vibrational cycle while the bullet is still in the barrel. The bend resembles what you see when you pull a rope taught and crack the end like a whip to send a transverse wave down its length. The recoil's vertical component pulls an upward bend into roguhly the first two thirds of its length. The muzzle is too far away for the speed of the transverse wave to reach it before the trough following the first bend occurs and turns the corner to swing the muzzle up. Thus it turns the corner at something close to the third harmonic node. It is the recoil moment's application of angular momentum from the receiver that forces this deflection profile, which is why it is dominant, rather than the first harmonic or any other harmonic. It's pure mechanics. Indeed, Varmint Al's conclusion is that the deformations are far more important to muzzle position than any natural harmonic or vibrating mode. It does, however, happen that the bend from this whip crack is right about at the third harmonic node, so you can roughly estimate timing from it. It is important, though, to realize the barrel isn't actually ringing yet, because the string isn't done being plucked.

So the barrel isn't actually ringing at the point the bullet exits in the animation. Instead, the muzzle deflection is only about 90° into what the first cycle of a third harmonic mode vibration would be at the time the bullet exits. If we take your barrel with a 63 Hz fundamental mode, the third harmonic is 189 Hz, which has a periodicity of 5.29 milliseconds (yes, I really do mean milliseconds this time). 1/4 of the way into that first period is a rough approximation of the bullet exit time, so that's at about 1.3 milliseconds. Pretty typical of medium power cartridge barrel times. Other barrels will have other deflection profiles, which accounts, in part, for why tuning them works at all.

Of course, there is also Chris Long's pressure wave theory. It's another form of deformation. I'm still not 100% sold on the idea except to say it does seem empirically to be synchronous with multiple barrel times at which groups shrink. Whether it is a primary or adjunct factor, I can't definitively say.

Gunplummer makes an important point of principle. The whole phenomenon of load tuning is gun and ammo synergy. If you have a bad barrel or one in need of recrowning, have bad bedding, need bolt lug lapping, have loose scope mounts, etcetera, the gun isn't going to shoot well with the best ammo you can possibly build for it. Similarly though, you could take the best benchrest gun ever made and if you load pulled surplus bullets from the Far East, bullets with dinged bases or unevenly thick jackets, fill the case poorly with a powder too slow to ignite consistently, use charge weights that vary all over the map, seat some primers hard while leaving others proud of the case head and everything inbetween, it won't shoot well either. You need the best of both to get the best precision shooting.

I've previously advised people with a new (to them) gun, to pick up a box of a good grade commercial match ammo, like Federal Gold Medal Match, and see what the gun will do with that before they embark on a load development program. If it fires a shotgun pattern with that ammo, they need work on the gun first. On the other hand, if it fires an moa or better, or if it fires any other commercial ammo and moa or better, they have a gun that will likely respond at least some (if not a lot) to load tuning.

The reason for the above is the bigger the initial group, the more difficult any improvement is to see. Group diameters caused by different independent error sources combine as the square root of the sum of the squares of the individual group diameters they would cause in an otherwise perfect gun. This means that an improvement that would improve a 1/2 inch group to a 1/4 inch group will only improve a two inch group by about 1/32 of an inch. Pretty hard to see. The point is, get the big group errors tamed first, then worry about improvements that only do fine tuning.

Last edited by Unclenick; March 25, 2012 at 03:49 PM.
Bart B. is offline  
Old March 24, 2012, 06:06 PM   #33
F. Guffey
Senior Member
 
Join Date: July 18, 2008
Posts: 2,738
"This whole thread is about "Feel good" extra work. I remember a '17 Enfield that after resizeing the brass it had gained about an average of .020-.025 in length. That is because military chambers are different. At 100 yards it......"

It is not my job to make you feel good, I will say had you put more extra work into your effort you would not have made the same wild guesstimate of a conclusion. You did not measure the cases before you fired the cases, do not feel lonely, that is a common practice with loaders.

You did not check the length of the chamber before you fired, again, a common bad habit among reloaders, you did/do not know the effect the chamber had/has on a case when fired, me? I determine head space first, then form, then fire. Without knowing the difference in length between the case from the head of the case to its shoulder and the length of the chamber from the bolt face to the shoulder of the chamber, you do not know if the length of the case increased from the head of the case to its shoulder, point being?
When sizing reloaders believe they are bumping as in "I bump my shoulder back etc.,etc.. and it is beyond their comprehensions when forming/sizing part of the shoulder becomes part of the neck and part of the case body become part of the shoulder, the shoulder did/does not move, the shoulder is still there where it was when the case was fired, the difference? the die forms another shoulder.

So, when you sized the fired cases the length increases when the new neck was formed, again, because the neck did not move and when sizing the shoulder is not bumped, a better term would be 'wreck' as in change.

And the Military chamber is different?

F. Guffey
F. Guffey is online now  
Old March 24, 2012, 07:25 PM   #34
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Mr. Guffey, your comments.....
Quote:
When sizing reloaders believe they are bumping as in "I bump my shoulder back etc.,etc.. and it is beyond their comprehensions when forming/sizing part of the shoulder becomes part of the neck and part of the case body become part of the shoulder, the shoulder did/does not move, the shoulder is still there where it was when the case was fired, the difference?
.....are way, way out of line. We're all smart enough to know that. We also know that if one sizes a .30-06 case into a .308 Win. one and trims the case length back to 2.010 inch, the then new .308 Win. case shoulder is that sloped section between the back of the neck and front of the body. We don't care that the old .30-06 shoulder metal is now in the neck; we figured that out a long time ago.

Geeeze, Guf, give us a break. Your rants are getting past the rediculous stage.
Bart B. is offline  
Old March 24, 2012, 10:09 PM   #35
Gunplummer
Senior Member
 
Join Date: March 11, 2010
Location: South East Pa.
Posts: 1,474
Amen. Yes, the chambers and brass specs for the military are different from SAAMI specs. Period. I made the reamer for the die set he had. I would not guarantee that brass from another die would chamber. Die sets have tolerance also. If you want to get into neck sizing, what a bunch of crap. I have had numerous problems over the years from people that neck size, especially pump and lever guns. "Do you reload?" became a standard question for me before checking a gun. Check out some brass at the range and see how the bulge usually is off to one side. It could be a series of alignment problems or just a large chamber with the shell off to one side when it goes bang. When you neck size, what makes you think that shell is going back in the chamber the way it came out? A good bolt action will cam it in but the base of the case will not sit on the bolt face flat without twisting the case. A good indication is brass rubbed off on the face of the bolt or bolt lip. There is a lot more there than mentioned in the load books.
Gunplummer is offline  
Old March 25, 2012, 07:03 AM   #36
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Gunplumber, your comment below is interesting:
Quote:
Check out some brass at the range and see how the bulge usually is off to one side. It could be a series of alignment problems or just a large chamber with the shell off to one side when it goes bang.
That bulge is typically just in front of the extractor groove and it's as common as trees in a forest. Having cut the head off several cases so bulged and measured case wall thickness all the way around, one thing was easily learned. The thinnest part of the case wall bulges out. When case wall thickness is very uniform, there's typically no uneven bulge.

Virtually all cases get pushed against the chamber wall at their back end by the extractor. So the back of the cases are all off center in the chamber when the firing pin strikes their primer. (Note: there may be some straightening or better alignment of the back end of a bottleneck case to the chamber axis as its shoulder centers in the chamber shoulder from firing pin impact.) Extractors are spring loaded and press the case rim off dead center on the bolt face. Mauser claw style ones press the case head to the left in right-hand actions. Those sliding ones in the bolt head like Winchester's post-'64 push feeds push the case head up when the bolt's closed. In any instance, the head of the case gets pushed as far as the chamber or bolt face recess allows.

Indexing rounds in the chamber with a mark on them showing where the extractor pushes them, firing the round then noting where the bulge is shows interesting data. Careful inspection of new cases show where the extractor scared the case as it was chambered. And a magnifying glass reveals firing pin imprint details on the primer (especially if you file a flat on its round edge to leave a significant mark in the primer dimple); another way to see how the case was indexed in the chamber when it fired. The case bulge is seldom at the point where the extractor pushed the case head off the chamber centerline. Proof to me that that bulge is common only to the thinnest part of the case wall in front of the extractor rim.

Your other comment about case heads against bolt faces is good; few folks know about this:
Quote:
When you neck size, what makes you think that shell is going back in the chamber the way it came out? A good bolt action will cam it in but the base of the case will not sit on the bolt face flat without twisting the case. A good indication is brass rubbed off on the face of the bolt or bolt lip. There is a lot more there than mentioned in the load books.
Few factory rifle bolt faces are square with the chamber axis. It's common for one point at its edge will be a few thousandths further forward than a point opposite it. Firing a brand spankin' new case with a perfectly square case head in such a rifle makes that case head flatten against the bolt face at the angle of the bolt face and pretty much stay there. Neither full length nor neck only sizing squares that unsquare case head back to square. When that round's chambered again and not indexed such that it matches the bolt face, there's two problems.

One is headspace; depending on how the case indexes against the bolt face, the clearance between the case and chamber lengthwise will vary a few to several thousandths. Stand a fired case on a flat surface against a V shaped object then rotate the case. If the head's out of square, the case mouth will enscribe a circle and not rotate about its center. The more the case mouth spins off its center, the more out of square the case head is.

The other is accuracy. Tests have shown that when the high point of the case head is aligned with the locking lugs on a squared up case head, the barrel whips such that its muzzle shoots bullets away further away from group center than when elsewhere. Square case heads shot against squared bolt faces shoot most accurate and stay square when sized for reloading. An unsquare case head against an unsquare bolt face is bad for best accuracy. Which explains why smart 'smiths square up bolt faces if best accuracy is important. Military rifle teams learned this decades ago when they tried to reload fired 7.62 NATO match ammo cases for their M14 and M1 service rifles. The best of those rifles would shoot all day long inside 4 inches at 600 yards with new commercial match ammo. Full length sizing and reloading those cases resulted in no better than about a foot at 600. None of the 'smiths rebuilding those rifles squared up their bolt faces.

One interesting thing Palma Team members learned about case head squareness. New ammo's typically the rule for international competition; everybody uses the same lot of ammo. Its case heads are fairly square but sometimes those at the limit of specs will be shot. The more lugs there are on the bolt, the more accurate those rounds will shoot. Which is why 3- or 4-lug actions are favored for this type of competition. A British riflesmith in the early 1970's, George Swenson, designed the first 4-lug action with very square up bolt faces to shoot their arsenal made 7.62 NATO ammo (the only type allowed in their fullbore long range matches) and it was an instant success. Since then, other makes have come on the market.

Last edited by Bart B.; March 25, 2012 at 07:43 AM.
Bart B. is offline  
Old March 25, 2012, 08:50 AM   #37
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
mrawesome22 thinks:
Quote:
... if you aren't using brass that has been meticulously prepped and sorted and checked for runout, all this oal business could be for naught.

Rounds that are not concentric with the same internal volume and/or have a sloppy fit in the chamber will be all over the paper no matter how great the powder charge or how far they are off the rifling.
This flies in the face of military semiauto match rifles with huge mil spec chambers shooting commercial .308 Win. match ammo with minimum case dimensions staying inside 4 inches at 600 yards all day long. And do so starting out with .020" jump to rifling in a new barrel to .100" at 3000 to 4000 rounds later when the barrel's worn enough to notice accuracy falling off.

And Sierra Bullets' first Ballistic Tech who tested virtually all their bullets for accuracy in super match grade barrels fitted to rail guns with chambers at or virtually equal to SAAMI specs claimed: "the round has to fit the chamber like a **** in a punch bowl." He (as well as so many other top high power match rifle competitors) felt and still feel the same way. Sloppy fit of case to chamber diameter wise is ok but headspace clearance range has to be a small spread. For rimless bottleneck cases, one with a sloppy fit diameter wise will align the bullet just as well centered on the bore when fired as one with a tight or minumum clearance case fit will.

Last edited by Bart B.; March 25, 2012 at 09:51 AM.
Bart B. is offline  
Old March 25, 2012, 03:51 PM   #38
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,314
Quote:
Originally Posted by Bart B.
Unclenick, you mentioned:
Quote:
A lot of the barrel time sweet spots are several tens of milliseconds wide. . .
My bad. I thought microseconds and typed milliseconds. I'll go back and fix it. Figure a bullet going 2500 fps will have 33μS/inch of travel. A load that stays accurate for a ±1% of powder charge in a .308 (about ±0.4 grains; not uncommon to find) will run just about ±32μS according to QuickLOAD, so almost a 2" span of barrel length. This explains why, in a post you had in another thread, the Garand with its muzzle funneled back 3/4" might not show any loss of accuracy timing with a good load tuned to a full length of rifling.

If you look at Varmint Al's animated FEA of a rifle firing (second image below first) you'll see his muzzle doesn't complete any vibrational cycle while the bullet is still in the barrel. The bend resembles what you see when you pull a rope taught and crack the end like a whip to send a transverse wave down its length. The recoil's vertical component pulls an upward bend into roguhly the first two thirds of its length. The muzzle is too far away for the speed of the transverse wave to reach it before the trough following the first bend occurs and turns the corner to swing the muzzle up. Thus it turns the corner at something close to the third harmonic node. It is the recoil moment's application of angular momentum from the receiver that forces this deflection profile, which is why it is dominant, rather than the first harmonic or any other harmonic. It's pure mechanics. Indeed, Varmint Al's conclusion is that the deformations are far more important to muzzle position than any natural harmonic or vibrating mode. It does, however, happen that the bend from this whip crack is right about at the third harmonic node, so you can roughly estimate timing from it. It is important, though, to realize the barrel isn't actually ringing yet, because the string isn't done being plucked.

So the barrel isn't actually ringing at the point the bullet exits in the animation. Instead, the muzzle deflection is only about 90° into what the first cycle of a third harmonic mode vibration would be at the time the bullet exits. If we take your barrel with a 63 Hz fundamental mode, the third harmonic is 189 Hz, which has a periodicity of 5.29 milliseconds (yes, I really do mean milliseconds this time). 1/4 of the way into that first period is a rough approximation of the bullet exit time, so that's at about 1.3 milliseconds. Pretty typical of medium power cartridge barrel times. Other barrels will have other deflection profiles, which accounts, in part, for why tuning them works at all.

Of course, there is also Chris Long's pressure wave theory. It's another form of deformation. I'm still not 100% sold on the idea except to say it does seem empirically to be synchronous with multiple barrel times at which groups shrink. Whether it is a primary or adjunct factor, I can't definitively say.

Gunplummer makes an important point of principle. The whole phenomenon of load tuning is gun and ammo synergy. If you have a bad barrel or one in need of recrowning, have bad bedding, need bolt lug lapping, have loose scope mounts, etcetera, the gun isn't going to shoot well with the best ammo you can possibly build for it. Similarly though, you could take the best benchrest gun ever made and if you load pulled surplus bullets from the Far East, bullets with dinged bases or unevenly thick jackets, fill the case poorly with a powder too slow to ignite consistently, use charge weights that vary all over the map, seat some primers hard while leaving others proud of the case head and everything inbetween, it won't shoot well either. You need the best of both to get the best precision shooting.

I've previously advised people with a new (to them) gun, to pick up a box of a good grade commercial match ammo, like Federal Gold Medal Match, and see what the gun will do with that before they embark on a load development program. If it fires a shotgun pattern with that ammo, they need work on the gun first. On the other hand, if it fires an moa or better, or if it fires any other commercial ammo and moa or better, they have a gun that will likely respond at least some (if not a lot) to load tuning.

The reason for the above is the bigger the initial group, the more difficult any improvement is to see. Group diameters caused by different independent error sources combine as the square root of the sum of the squares of the individual group diameters they would cause in an otherwise perfect gun. This means that an improvement that would improve a 1/2 inch group to a 1/4 inch group will only improve a two inch group by about 1/32 of an inch. Pretty hard to see. The point is, get the big group errors tamed first, then worry about improvements that only do fine tuning.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member

Last edited by Unclenick; March 26, 2012 at 09:09 PM.
Unclenick is offline  
Old March 25, 2012, 09:44 PM   #39
Gunplummer
Senior Member
 
Join Date: March 11, 2010
Location: South East Pa.
Posts: 1,474
Bart B.

Not enough examples tested. Lots of guns use bolts that have extractors that do not pressure the round. One example is the 99 Savage, if the barrel was made properly. The extractor rides up a groove in the barrel and exerts no pressure. A lot of claw extractors ride in the rim groove and put no pressure on the cartridge. The amount of pressure has a lot to do with it.
Gunplummer is offline  
Old March 25, 2012, 10:09 PM   #40
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Gunplummer, I don't know what you mean by "not enough samples tested."

But I agree that some extractors put no pressure against the case. These types don't hold the empty case too well in the bolt face and are sometimes subject to extraction problems.

Which rifle make/models besides the Savage do this? All the Winchester 70's, Remington 7XX and 40X, Paramount, Mauser plus several single shot bolt actions have extractors that press the case sideways against the recessed bolt face and hold it there during extraction.

Doesn't matter anyway as there's not enough slop at the back of the case body to the chamber wall anyway that'll effect accuracy.

Sierra Bullets in the reloading manuals some years ago that loaded rounds rest in the bottom of the chamber due to gravity. Their ballistic tech who tested their bullets for accuracy, a good friend I shot a lot of matches with, knew better and tried to get them to change that. At the time, Sierra didn't. But it got removed some years later.
Bart B. is offline  
Old March 26, 2012, 07:48 AM   #41
F. Guffey
Senior Member
 
Join Date: July 18, 2008
Posts: 2,738
In Roy Dunlap’s book on gunsmithing are illustrations and specifications for chambers and cartridges, in the 30/06 section he list two chambers, one for the 30/06, the other for the M1 Garand. The M1 Garand was said to be different because of the additional clearance in the rear of the chamber, .0002+ to aid in extraction. The M1917 Remington and Winchester were very fine rifles, the Eddystone, quoting Roy Dunlap, was anyone's guess.
Again, I have one with .016 thousandths head space as in the chamber is longer by .016 thousandths from the bolt face to the shoulder of the chamber than the case is from the head of the case to its shoulder.

It is not easy to find cases long enough for that chamber so I use 280 Remington cases, I adjust the 30/06 forming die off the shell holder .014 thousands, raise the ram, form the case then finish by sizing with a full length sizer die and a .014 thousandths gap between the bottom of the die and and top of the shell holder. again, I use new and or once fired cases.

As to picking up and or purchasing brass at the range with perceived problems, I (have) purchase range brass, 280, 270, and 30/06 for .08 cents each with an additional 10 thrown in for each 100, JIC. My favorite cases are cases fired in trashy old chambers, again, I want cases that are long from the head of the case to its shoulder, I do not want cases that exceed maximum case length, for the 30/06, that would be 2.494. Trashy old chambers? Most of the brass purchased at the range have the the appearance of being bent, misaligned or deformed, seems when the bolt closes and the handle is rotated it gets dark in the chamber and the light goes out in the shooters head, on a control feed the case head is supported between the extractor and left side of the bolt, once the case chambers and the bolt rotates the support for the case head on the left side moves to the top, leaving the case head unsupported on the left side, that means nothing to those with ‘lights out’ for me and trashy old chambers? I separate cases, fired in push feed, fired in control feed, (Speaking of of push feed, I can not remember who it was that was hollering, seems they could not find the ‘three rings of steal’ promised by Remington, I had to holler back, look in your hand, it is in your hand, you removed the bolt, it is in your hand)

Epiphany: Gunplumer, I believe you had an epiphany, you chambered a round, pulled the trigger, fired then extracted a fired case, at that point in your story I am wondering when you, the gunplumer is going to start measuring, and then finally you full length size the case and then measure the length of the case and discover the case is .020”-.025” too long? The fact your cases increased in length has little to no value if you do not understand measuring before and again after. Full length sizing and moving the shoulder back is an illusion.

Military chambers are different? We ( I ) have thousands of military cases fired in military chambers with crimped primers, I have military 30/06 cases that are unfired, I have no fewer than 8 military type 30/06 rifles, I have take off barrels, and what does all this mean, I am going with Roy Dunlap, all 30/06 chambers were designed to fire the same ammunition, the M1 Garand, in the beginning had a generous? chamber.

The M1917, a gunsmith in Utah was credited with stretching receivers because of his methods and techniques, he was accused of using a field reject gage (only). My Eddystone with .016” head space never got to Utah, my M1917 that did get to Utah does not have a long chamber. As to the Utah’s smith and his methods, I can check the M1917’s head space, in thousandths, with a field reject gage, or a 280 Remington case without stretching the receiver, and I believe the Utah smith was smarter than his accusers.

I know Bart B. has all this figured out, the 308 Winchester, when fired in a 30/06 chamber head spaces on the case body/shoulder juncture, meaning the shoulder of the 308 W is not supported and when fired forms to the chamber. Then there are those that claim they fired 308 W ammo in a M1 Garand and claim the M1 handled like a doll buggy, and I upset them by asking about the gas system drop in pressure and case extraction/ejection, I ask, “Shouldn’t the shooter suspect something was wrong when cases had to be manually ejected” to me that is something the shooter would remember, time is a factor, when the 308W case formed to the chamber time elapsed, the time it took for the case to fill the chamber caused a drop in pressure etc., etc.. the 308 W is larger in diameter by .011” than the 30/06 chamber at the contact juncture between the 308W case body/shoulder juncture and chamber. Firing 308 W in a 30/06 chamber is a bad habit.

F. Guffey

Last edited by F. Guffey; March 26, 2012 at 07:53 AM.
F. Guffey is online now  
Old March 26, 2012, 07:52 AM   #42
Gunplummer
Senior Member
 
Join Date: March 11, 2010
Location: South East Pa.
Posts: 1,474
Many Mausers that were rebarreled fit the description. American brass is a loose fit. Arisakas are the same way. You take the bolt out, insert a live round in the bolt face (Remove F/P first!) and watch it hang down. Turn the bolt handle so it faces down and the bullet will probably fall out. There are no extraction problems there, that is the way it works. Extraction problems start with dirt, overheating, and bad reloading. I have test fired many a rebarrel or new bolt with out the extractor installed. Once you open the bolt most cases fall out when you stand the rifle upright, if you do it right away. If you have extraction problems it usually means something is wrong or you are doing something wrong. If most extractors were that tight, I doubt there would be so many empty cases laying around with the primers slightly backed up. I go with the theory of "Where it lays is where it stays".
Gunplummer is offline  
Old March 26, 2012, 09:36 AM   #43
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Guffey comments:
Quote:
Then there are those that claim they fired 308 W ammo in a M1 Garand and claim the M1 handled like a doll buggy, and I upset them by asking about the gas system drop in pressure and case extraction/ejection, I ask, “Shouldn’t the shooter suspect something was wrong when cases had to be manually ejected” to me that is something the shooter would remember, time is a factor, when the 308W case formed to the chamber time elapsed, the time it took for the case to fill the chamber caused a drop in pressure etc., etc..
Is this another one of your baseless assumptions? Note that you're not upsetting me about this. Here's why.

Having seen dozens (hundreds?) of 7.62 NATO rounds (M80 ball and M118 match) fired in 30 caliber Garand chambers and all cycled the op rod and bolt well normally ejecting fired cases then loading the next one automatically, never ever seen any that had to be manualy ejected. Neither did the small arms instructors at Camp Elliott in the mid 1960's where USN recruits were trained in small arms use where most of this event happened. I've watched some folks shoot 10 rounds rapid fire in a minute with NATO ammo in a 30 caliber Garand without even noticing what was happening. The first indication of something amiss was empty cases without necks all over the place and only a smidgen of a shoulder coming down off the 1.97" or so long case body was visible. Cut most of the shoulder off a .30-06 case and you'll see what they look like.

There's plenty of port pressure to cycle a Garand op rod and bolt firing 7.62 NATO ammo in a 30 caliber Garand. While not quite as gusto as standard .30-06 ammo and no doubt at the lower end of specs, it nevertheless did a good job and no failures to cycle happened as far as I know.

Last edited by Bart B.; March 26, 2012 at 10:47 AM.
Bart B. is offline  
Old March 26, 2012, 10:28 AM   #44
Wyoredman
Senior Member
 
Join Date: September 6, 2011
Location: Wyoming
Posts: 1,257
This weekend I did a complete work up with H4350 and the bullets seated for a COAL of 2.680 so I could compare it to the workup I did at COAL of 2.650".

The results were surpising to say the least.

The loads for each test were as follows:
38.5 gr
39.0 gr
39.5 gr
40.0 gr

I found that the 2.680" test, the velocity for each round was about 50 fps more than the 2.650"

The real interesting thing was that at a COAL of 2.650", my tightest group was with the 40.0 gr charge (0.980), just under 1 MOA. With the 2.680" test, my best group was with the 38.5 gr charge at 0.750"! The 40 gr charge with the longer OAL was terrible at 1.5"+!
__________________
Go Pokes!
Go Rams!
Wyoredman is offline  
Old March 26, 2012, 10:40 AM   #45
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Wyoredman says:
Quote:
This weekend I did a complete work up with H4350 and the bullets seated for a COAL of 2.680 so I could compare it to the workup I did at COAL of 2.650".
I'd repeat that test at least two more times if you only shoot 5 rounds per group. The spread from worst to best group is too small to have the smallest be significant.
Bart B. is offline  
Old March 26, 2012, 10:04 PM   #46
Gunplummer
Senior Member
 
Join Date: March 11, 2010
Location: South East Pa.
Posts: 1,474
Guffy, I had a raccoon like you once. If I put a rubber fishing lure in a jar with a lid on it he would play with the jar for hours. Take the lid off and he would grab the fish, look at it, throw it down and wander off. I bet I could give you a dial calipers and get the same affect.
I don't know Roy Dunlap and if he wrote anything that made sense I suspect you twisted it around. I don't really care what you think either. Military chamber and brass specs are different than SAAMI specs. Period. The headspace is not even called off the same area of the shoulder. How many load books have warned about excessive pressure using milspec brass in SAAMI chambers because the brass is thicker? I have seen many empty cases that were stuck in the wrong gun (Yes, I was dumb enough to do it too) and it was not an illusion. The short cases soon became very long cases and the shoulder was definitely moving.
Gunplummer is offline  
Old March 27, 2012, 08:50 AM   #47
F. Guffey
Senior Member
 
Join Date: July 18, 2008
Posts: 2,738
You know what I am trying to do? Make you mad? What if I wasn’t?

I thought you were trying to show off, barrel time, milliseconds, something like 1.5/100000.

Back to the 308W fired in the M1 30/06 chamber, when fired and the case forms to the body of the chamber the 30/06 shoulder is .382” ahead of the 308W shoulder, that is a drop in pressure and a a big delay for the bullet, I will admit you have the ‘hint of the beginning of a shoulder’ at the mouth of the formed 308W case fired in a 30/06 chamber down pat, but, when the barrel time and millisecond thing is applied to the neck of the 308W neck? The neck normally expands .010” + or – when the neck is supported, when the neck is not supported the neck disappears and becomes part of the case body, when the neck of the case becomes part of the case body the shoulder of the case does not have support and as a results the hot high pressure metal cutting gas is escaping around the bullet before it, being heavier and with an additional .350”+ jump to the lands, can reach the rifling, so case expansion causes pressure to drop, gas escaping past the bullet causes a drop in pressure, and again when the neck expands and become part of the case body the bullet is left, almost, unsupported.

And I am sure if they were using a spacer they would have told you, backing the 308W ammo against the clip to get started and holding the ammo there is something that had to be worked out when 308W barrels were installed on the M1. Again, it is a mistake and or a bad habit to fire 308W in a 30/06 chamber, I want my cases to cover all of the chamber possible, all that hot high pressure metal cutting gas can not be doing the exposed area of the chamber any good.

F. Guffey
F. Guffey is online now  
Old March 27, 2012, 09:45 AM   #48
wncchester
Senior Member
 
Join Date: December 1, 2002
Posts: 2,832
Bart - Don't feed the troll!

-------------------------------------------------------

"When Mr. Stecker says a meaningful change is 0.002" to 0.005", I believe he means that is the limit of useful resolution of seating depth adjustments. In other words, that's the kind of round-to-round variation in ogive distance off the lands you normally find after seating bullets, so attempting to make adjustments any smaller for any purpose whatsoever is pointless."

Absolutely correct, amen. Few custom barreled target rifles are sensitive to such tiny seating differences and no factory guns at all.

All good loads have a 'window' of good accuracy where a few tenths of a grain or powder or a few thou of OAL won't make any noticable difference. Charging or seating at the ragged edge can be sensitive to changes in the wrong dirrection but, if we load in the middle of the window, small differences in a properly developed load should make no difference.

Book OAL is not a "recommendation" and it's no more a law than their powder listings; it's just what the book makers used for their firearms and can be expected to be safe in any properly chambered rig. Finding our best OAL is just as much a part of the game as finding the best powder charge.

Seating bullets long in a rifle will increase starting and peak pressure but that pressure increase will rarely have much useful effect on velocity. Seating deeper and using more powder, or a different powder, does that.

Last edited by wncchester; March 27, 2012 at 09:57 AM.
wncchester is offline  
Old March 27, 2012, 10:07 AM   #49
F. Guffey
Senior Member
 
Join Date: July 18, 2008
Posts: 2,738
Gunplummer,

This whole thread is about "Feel good" extra work. I remember a '17 Enfield that after resizeing the brass it had gained about an average of .020-.025 in length. That is because military chambers are different. At 100 yards it shot great with factory ammo. I did an 8x57 barrel for a guy and he wanted it built to the dies he had. He fired off half a box of the brand of brass he was using, resized and trimmed all to length. I took measurements off the brass, and will admit there is a lot of "Feel" involved when you do this. I did the chamber, we fired off the reloaded half a box of brass that was sized and trimmed, resized it and started measuring. Not one case was more than .001 longer than the original trimmed size. I doubt neck sizing is that close, and there are issues with that I won't go into here. It shot O.K. at 100 yards but not great. This Guy liked to play and tried all kinds of recipes and it never was a tack driver. A lot of the reloading advice is nonsense because the gun or barrel is not good enough to take advantage of it anyway.



I have no ideal why you are so angry, “feel good” is about helping someone, you claimed you chambered a round in an Enfield, pulled the trigger, extracted the case and then you full length sized the case, I believe that is a bad habit, I suggest you measure before chambering, again after firing and then again after full length sizing to minimum length, and if you do not know the length of the chamber from the bolt face to the shoulder of the chamber full length sizing to minimum length is another bad habit, as I have told you and told you I am the fan of cutting down on all that case travel.

“A lot of the reloading advice is nonsense because the gun or barrel is not good enough to take advantage of it anyway”

I do not agree with some advise given when every answer has a solution that includes “You need another tool” again, I am the fan of getting all the use I can out of every tool I have, my full length sizer dies are ‘versatile’ full length sizer dies, I form/size cases for short chambers, I form/size cases for long chambers with ‘versatile’ full length sizer dies. That is .012” shorter than minimum length to .014 longer than minimum length.

“It shot O.K. at 100 yards but not great” sounds just like my experience with Winchester, I wanted a chamber that fit my dies or I wanted them to make a set of dies fit their chamber, their chamber was was the ugliest chamber I have ever seen.

Again, I have a Rock Island 03 built in 1911, I have a Remington 03 built in 1942, I have rifles built after 1911 and before 1942, and I make gages, .012” shorter-.014” longer in thousandths, that is 26 gages, a reloader/shooter/collector neighbor of yours has a set, seems he was on a socially dysfunctional forum trying to get an answer about head space, at the time he had 10 plus 30/06 rifles, I contacted him, I informed him there was a smith/shooter/collector/machinist in North Carolina I was making gages for and making two sets would not require additional time and effort, so, I mailed him a set 6 years ago, I called him last last weak, his collection has moved from military to higher end type rifles, still, today, he uses the gages to check rifles before purchasing.

Point? He was having problems with a M1917 Eddystone, all the answers he got from the form were in lofty, vague and self serving terms, he called me after measuring the chamber, .016 thousands, he decided not to shoot the rifle, I explained to him the reason for sending the gages was about reloading, I explained to him by knowing the length of the chamber I could form cases that fit, he chose not to reload for that M1917, and he said he sold the rifle and made the buyer aware of the long chamber.

And I was purchasing parts, a man with a very fine rifle with an unusual chamber came in to have the head space checked, the smith informed the owner of that very fine rifle he could not check the head space on that rifle because he did not have a gage, the owner of the very fine rifle left, I informed the smith I could check the head space on that rifle with out a gage at least 2 different ways, and the smith with class leaned forward and ask “How?” He was/is a good listener, when finished he said, “I would have never thought of that and never considered it was possible”.

Unclenick should expect better from me, so I ask him to forgive me for my part.

The chamber did not change, the method for deterring the length of the chamber from the bolt face to the shoulder did, when making a comparator as in measuring before firing and after firing I make up datums, to do that is to understand what a datum is.

F. Guffey

Last edited by F. Guffey; March 27, 2012 at 10:11 AM. Reason: change has to had
F. Guffey is online now  
Old March 27, 2012, 12:45 PM   #50
Gunplummer
Senior Member
 
Join Date: March 11, 2010
Location: South East Pa.
Posts: 1,474
I have made reamers for guys that wanted to use "Special Brass". We call that a wildcat cartridge. I have "Made" one type of case out of another because I could not get the proper brass and that is what you are doing. The correct brass has different specs as does the chamber. I don't know what you are mumbling about when it comes to making gages. You don't even know the differences in the specs. Before you talk down to everybody else here, why don't you tell us exactly where on the shoulder the SAAMI and MILSPECS arre called from?
Gunplummer is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 08:15 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.18781 seconds with 7 queries