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Old February 14, 2013, 03:29 PM   #26
Bart B.
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Guffey sez:
Quote:
Bart B. you started by declaring the case had a head space, gages that measure case length from the shoulder to the head of the case are case length gages, some are comparators used to measure case length
Nope. I didn't state that at all.
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Old February 14, 2013, 04:22 PM   #27
Hummer70
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A MO gage is the ideal all around most helpful thing I have bought in years.

You can load a case, measure the datum on the shoulder, fire the case and measure the fired case and know exactly how far forward the shoulder has moved.

Then you can adjust your FL die to move the shoulder back as little as .001" or all the way to GO.

You can also tell if your dies are properly chambered. I have had to trim about 15 FL dies to get them to size properly.

I have three Mo gages and they are immensely valueable to let me know exactly where I am in the sizing game.
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Old February 14, 2013, 11:59 PM   #28
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Bart B., I have to admit I am somewhat biased in accepting your information. We share the naval tradition. I'm USMC retired. Lots of respect for my USN brethren.

I've got a fine .243 bolt gun set up. I'm going to run some informal tests to compare NS to FLS over the next few months--if the weather permits. I'm open to the fact that FLS may be better. Will post here, eventually, to let folks know how it turns out.
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Old February 15, 2013, 07:10 AM   #29
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Your test vehicle is likely to give different results because a bolt gun is a totally different animal than a gas gun. IF your rifle is set up right both lugs are contacting equally and the barrel may be contacting front of receiver 360° around and your bolt face may be square.

The M14 in issue condition is known as the worst performing rifle we ever fielded. I worked product engineering for the Army Small Cal Lab at Picatinny Arsenal and I had engineering responsibility for the M14 until the Chief transferred me to the Dover Devil MG project. While there my board was adjacent to Julio Savioli who was the draftsman for the M14 rifle and his name is on all the drawings for it. Al Cole was engineer in charge of the M14 and he was also a friend. Savy (as we called him) was a wealth of information on the M14 and had all kinds of stories about it as he not only did the drawings, he was in on the field testing.

First off consider the requirement facts from the engineering files from the government weapons production efforts.

1. acceptance accuracy for 1903 Springfield was 3" at 100 yards.
2. acceptance accuracy for M1 Garand was 5" at 100 yards.
3. acceptance accuracy for M14 was 5.5" at 100 yards and was waivered continually as it could not meet that.
4. acceptance accuracy for M16 series is 4.5" at 100 yards.

From SAAMI we have a recommendation of 3" at 100 yards and it is up to the vendor whether he wants to meet this or not.

H&R also made M14s and M1s and the contracts were shut down due to poor QA.

The M14 if rebuilt correctly and very few can do so is capable of acceptable accuracy. For instance the Army MTU rebuild program with rifle fired from machine rest was 10 shots in 4.5" at 300 yards. Some would go to 3" but rarely. A good bolt gun will shoot in 2" at 300 yards.

The TRW weapons were at one time thought to be good but MTU set up some exotic measurement fixture and figured out the threads in the receiver were not at right angle to the front of the receiver and from then on all their builds were on SA receivers.

If you will get a copy of Hinnant's book entitled "The Guide to Precision Rifle Barrel Fitting" you will read about a lot of the headaches manufacturers allow to get out the door even with bolt guns.

The out of square problems Bart refers to is really quite common in many vendors weapons. On a bolt gun these are easily corrected with a good lathe.

Check out http://www.bryantcustom.com/articles/true.htm which will give you a working knowledge of what has to be done to make a rifle shoot well.

These processes while they can be done on a M14 are problematical because if you chuck up a M14 receiver to square the front of the receiver and you take material off the front of it, that destroys the thread timing for the barrel.

Military rifles are set up to be rebuildable at depot by just taking off a tired barrel and replacing with new. The new barrels have the threads timed so that it will snug up right before 12:00 o'clock and the barrel can be torqued on. Thusly the interface of the receiver and barrel contact points is extremely critical and must be controlled to tight tolerances. If material is removed from front of receiver the replacement barrel will not contact the shoulder with enough "crush" to have the barrel "time up" at 12:00 o'clock.

Now with after market barrels you can square the receiver face and twick the barrel to get it to time at 12:00 a bit easier but squaring the threads is still problematical.

The 1903 and 03A3 rifles were built the same way and they too have thread alignment issues. For instance I had a barrel all threaded up for 03A3 and I had three actions with no barrels that had been squared. I screwed that barrel into one receiver and it contacted first a 4:00, the next one contacted at 9:00 and the third one contacted 360°. Which means the threads were out of square on the other two actions and on the money on the third one.

The M14 can have other problems wherein the bolt lugs don't bear equally.

A quick and dirty way to tell whether you have a problem is to examine your striker indent on a fired case. The ideal barrel to action set up is to have the bore center line of the barrel and the bore center line of the action in perfect alignment. If the barrel threads are out of square the line has a bend and it first shows up as off center striker hits. You will also find bolts with striker openings drill off center as well.

The industry "recommendation" allows for 1/2 the diameter of the striker indent to be off center. Medium bolt strikers measure around .060 diameter thusly the off center condition can be .030" out of alignment.

Frankford Arsenal tested millions of primers in a big study in the 50s and it was determined the offset of the striker indent had no detrimental ignition reliability up to .020" offset but after .020 the misfire rate is increased dramatically. Bottom line is the ammo boys determine reliability is compromised over .020" and the weapon boys produce rifles with .030" offset to meet production. It is a fact of life in mass production.

Now if you want to see precision take a look at the Barnard actions and the other actions the current crop of Palma Team shooters use. Their cases come out and show visually dead center striker indents and the rifles all shoot very well.

As Bart indicates you still have the problem of out of square case heads and bolt face out of square problems. If you will dig back about 1978 time frame there was a big article by a guy named Creighton Audette who did a lot of study on this and determined out of square case heads set up even more problems and if your bolt face is out of square, the threads are out of square and the bolt lugs don't contact evenly then you have compounded problems.

So basically while your rifle may shoot much better than others is it perhaps the fact is yours has a straighter bore/action centerline, lugs contact and bolt face is more square.

Case in point I had a new commercial rifle I got in 2005 and it shot horizontal groups that holes tended to touch or almost touch. I had a looksee at bolt lugs and bottom lug was not touching. I lapped in top lug and rifle started shooting round groups.

There are other problems to be experienced such as barrel is not properly stress relieved and starts to walk. Worst I ever had was a H&R breakdown rifle in 223. It consistantly shot a 3 shot group 1.5" wide and 10" high at 100. A call to H&R revealed they did not stress relieve barrels at all. They replaced barrel and it shot 2" at 100 in a round group.

I had two very good friends who were the ordnance types for the US Secret Service. One was formerly an ammo tech at Frankford Arsenal and the other built the ammo acceptance rifles while there. At USSS they did similar except one built all the sniper rifles. They too told me that their testing with Fed Match showed what Bart has alluded to. With their budget they could handload every last round for their counter sniper rifles yet they do not.

The problem is finding factory ammo that shoots well in the first place as most factory ammo has cannelures which is a perfect thing to do to a bullet to destroy it's accuracy. Mass produced hunting bullets for the industry can be bested by using Sierra matchkings about 99% of the time so if you test hunting ammo and then handload Sierras your data will show handload is best but it is because of the quality of the projectile thus your data will be skewed.

This by no means is a complete list of problems that can be encountered and need to be overcome to achieve that one hole rifle. Bart has been around the block a few times and has experienced things 99.9% of others never dream about.

On my gas guns I FL size. If I place round in chamber I ease the op rod about half way down and release it. If I am necking only with a gas gun I will load them long to be close to the lands (within .020") and place in chamber with easy let down. Also my gas cylinder plug has an extra vent hole to bleed off port pressure a bit. My Tanker Garand has a much larger hole in gas plug to bleed off excess pressures so ejection angle is correct.

I also apply Mobil 1 synthetic motor oil to gas ports or let run down op rod to keep the carbon build down.

In standing I will just pop round in mag and drop it. On my bolt guns most of them I FL size for with dies matched to the chamber so I don't move brass over .002" when sizing. Some I neck size the entire neck only and not the body. Some I partially neck size but on my bolt guns the chambers are much tighter. I guess you could say on the whole I FL all rapid fire. If you will look closely at Fed Match you will see a transistion angle between neck and shoulder that is not duplicatable in FL or Neck dies.

If you have a chrono you might also check your SD for a 30 round string between FL and neck sized. Basically shoot ten and tally, shoot next ten and tally and last 10 and tally. Shoot at 45 second intervals. You may well find a significant difference. SD of 10 or less was Marine Corps ammo room standard at Quantico for Marine Corps team.
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Old February 15, 2013, 08:15 AM   #30
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Question on Neck Sizing .308 for M1A

Quote:
Originally Posted by Bart B. View Post
wyobohunter, exactly what does it depend on? You may have a good point of view and many would benefit from knowing what it is. You jumped into this conversation and that's fine by me, so you're not staying out of it.
It depends on your rifle, on wether your groups shrink or not. Typing a dissertation on what the bench guys do does not change the very simple fact that some rifles will enjoy smaller groups from fire forming, some will not. It is silly to make an assumption/hypothesis and name it fact when it simply is not.

I said I was staying out of it because it is pointless to argue with folks that are convinced and completely unbound by the burden of sense.

Now I return to it because I was addressed directly. And I don't like it when misinformation is regurgitated. X number of bench rest shooters FL size, so what? Are all of my conditions the same as theirs? Nope.

So, should I neck or FL size? It depends. I have to test one vs the other to know the answer, no one can tell me that and presupposition is strong indication of cut and paste ignorance.

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Old February 15, 2013, 09:09 AM   #31
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GunAddict1962, how does the .243 and .308 Win cases fit their chambers when they're loaded and fired?

What's the difference between a .308 round and .243 round being chambered and fired in a .308 rifle as far as bullet alignment with the bore?
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Old February 15, 2013, 11:10 AM   #32
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“Bart B. you started by declaring the case had a head space” Now? There are others that have no practice understanding of what is going on are locked up in the “Repeat after me....etc.,etc..” Syndrome.

Again, tool manufacturers took liberties, they labeled their comparators ‘HEAD SPACE GAGES’ the company that makes one of the most humble of tools, The L.E. Wilson case gage, labeled their gage a case (length) gage. Instead of taking the Wilson gage apart I drove a case into the gage while it was setting on a block of lead, with a drift, after the case head disappeared from sight I drove it back out. On the shoulder of the case was the impring of ‘A DATUM!!!” with a radius of .375”. Since then I collect datums, I make datums and I purchase datums.

The case has a length, the Wilson case gage measures two lengths, one from the DATUM back, the other from the DATUM forward, the only measurement.The only one I am concerned with is the one from the datum/shoulder back to the case head. The case does not have a head space, with practice a reloader can off set head space with the length of the case if they can avoid the “REPEAT AFTER ME syndrome”.

One more time: I have a non-Weatherby with a non-Weatherby chamber. The serial number is somewhere behind a row of 00000 (zeros) and then something like 187. It shoots one hole groups, I started with 4 boxes of Federal ammo, etc.. then Hornady, Remington, and Winchester. Shoot two rounds then zero. AMMO? RIFLE?

SAME STORY as told before, I have a Winchester Model 70 chambered in 300 Winchester Magnum, ammo fired in the non-Weatherby would chamber in the Model 70 without touching the chamber. the Model 70 shot patterns (shotgun like). Sizing cases? Cases fired in the Model 70 could not be sized, no case was ever designed to take that kind of punishment, no press and or dies were designed for that amount of abuse, Winchester thought I was impossible when I told them I wanted a chamber that fit my dies or I wanted Winchester dies to fit their chamber.

Again, I bid on and won a rifle that was bait for compulsive laughers on gun forms, hands down, voted the ‘UGLIEST RIFLE EVER BUILT BY BUBBA’, I could not see how someone could build a rifle that ugly without knowing what they were doing, I took it to the range with 12 different loads of 10 rounds each, same thing as the non-Weatherby, There was nothing I could do to improve accuracy, only problem it got hot. Not a problem, I normally take at least 8 rifles to the range.

AMMO for the “UGLIEST RIFLE EVER BUILT BY BUBBA”, Total disregard for the chamber, but the cases after firing would chamber in a chamber gage made for another rifle. Not the chamber gage made like a tight fitting Wilson case gage but the chamber gage with case head protrusion.

Bart B. the case has a length, when using the Wilson case gage the case has two length, a gage used to measure case length is not a head space gage. BUT the case length gage can be checked with a head space gage for accuracy, something verifying (foreign term), and the head space gage can be used to check the accuracy of a full length sizer die, and that is the reason I do not get all tangled up in lofty terms like manufactures specifications and ‘the ammo manufacturers tolerances, tolerance with no value, I verify, I have chambers, I have presses, dies and shell holders, and, I am the fan of standards, transfers and verifying.

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Old February 15, 2013, 11:28 AM   #33
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“What's the difference between a .308 round and .243 round being chambered and fired in a .308 rifle as far as bullet alignment with the bore?”

Bart B. I did not get an answer, “knurls on the case body”, I suggested the knurls on the case body would tighten the case in the chamber and aid in alignment with the bore.

Anyone that insist on full length sizing has no regard for bullet alignment, Me? I am the fan of cutting down on all that case travel, I am the fan of knowing the length of the chamber from the bolt face to the shoulder of the chamber, again, my presses and dies have threads, I can take advantage of the feature or I can mindlessly screw the die down to and below the shell holder, it is a choice, problem? A reloader should know why they choose one method/technique over the other, instead of “I do it because I read it on the Internet.

thinkers? or followers.

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Old February 15, 2013, 04:31 PM   #34
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Quote:
Slamfire
Sir, would it be possible for you to supply more information regarding this condition? This is a very interesting event.
Mark: Pulling teeth from Dragons is easier than getting any details, never mind pictures, of slamfires. This event was posted here:
http://m14forum.com/m14/120119-out-b...ire-today.html

The dominant posters over at M14Forum do not believe that primers vary by sensitivity, do not believe a M1/M14/M1a can slamfire due to a sensitive primer, do not believe that a M1a can slamfire unless the round has a high primer or there is something mechanically wrong with the rifle, but they accept bumpfires as causing slamfires. If you notice in the thread, the poster bowed out because no one believed that his primers were below the case head and therefore the slamfire had to be his fault.

Happened in another thread where the shooter was using factory ammunition and the rifle fired in battery and they would not accept that he either did not bump fire the rifle or have high primers. Upset that poster and he never replied again.

The first poster said the rifle had been sent off to Springfield Armory before he bugged out. You are welcome to log into that forum and ask.


It would be interesting to find out from you, someone who worked in the Ordnance Department, about the frequency of slamfires in Garands and M14’s. And why the tradition has been that “only high primers and worn out receiver bridges” was the only allowed explanation for slamfires in these mechanisms.

It is my considered opinion, after talking to enough people who have had slamfires, that this mechanism is at particular risk of an out of battery slamfire with a tight case and a sensitive primer. I also have accounts of out of battery slamfires with LC ammunition (almost all Garand incidents) and many in battery slamfires with factory, a few LC, and an increasing number of reports of Garands slamfiring inbattery with Greek surplus.


Quote:
Could you measure:

1.the inside diameter of the Wilson case gage at the bottom with hopefully a digital caliper or hole mic? I have measured three Wilson case gages for .260, 7/08 and 308 and I get measurements of .4725, .474 and .475. Since the chamber dimensions are called for at .471-.473 range and assuming your Wilson gage measures like mine then every fired 308 case in history should fit in your gage with a .474 or .475 base dimension.
I can measure my Wilson gage and my “homemade gage”, though the “home made gage” was made by Gene Barnett, the barrel maker, with the same reamers he uses in cutting his rifle chambers. I don’t consider them less quality than the Wilson even though he is less well known.

I won't get around to this for a couple of days as there are several mid range and long range matches this weekend.

Have a good weekend.
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Old February 15, 2013, 05:58 PM   #35
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Question on Neck Sizing .308 for M1A

It seems (from the link Slamfire provided) that the most likely cause of that particular OOB slamfire was single loading a cartridge into the chamber and letting the bolt fly forward. Yikes, never do that!

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Old February 15, 2013, 08:31 PM   #36
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Slamfire, I have known Gene Barnett about 30+ years I reckon and have received probably half a dozen of his quality barrels.

The problem with malfunction investigations is that you never get the full story. You never see the case that did the deed. You never get to interview the shooter.

It is human nature not to admit you have screwed up.

It is kind of like going to a killing where a guy has been shot 35 times with a 45-70 and there is no brass on the floor, no rifle and it is declared suicide because someone said he was thinking about killing himself to several folks and he was seen reading an article about 45-70s 13 years ago.

I have personally scored several Delta Sierrras and I could see their primers were above the surface and I told them they were doing something dangerous and the response was "I never had any problems."

I got up, moved my stool and scope to place their head between me and the chamber and waited for the "news" and they got away with it.

Forrest Gump's mother said it best, "Stupid is as stupid does."

I know one of the guys on that forum and provided him lots of poop for his books.

I was in no hurry to go distinguished high power and it took me ten years to get it as I shot a gas gun every third match to keep my average in the Master Class as I did not want to get into High Master. I never saw or heard of a slam fire with M14s or M1As during the whole time and we never got any M14 rifles in for catastrophic failure analysis. Whoops forgot, we had one. The boys at Benning welded a op rod guide to a barrel and the barrel let go just short of the welded area.

There were a number of M14 barrel failures with one make of barrel and the investigation determined the vendor that supplied his steel had sent him a bad run with bad things therein. They were evaluated with SEM and determined it was not the barrel makers fault but the steel vendors fault.

I was at Perry and was in the pits when we heard one blow on the 200 yard line. I immediately went to the line and heard the guy asked if he had got a notice of recall for that barrel manufacturer and he admitted he had got a card saying a new barrel would be provided free, return rifle immediately.

He said it was shooting good and he thought he would finish out the season and have a new barrel for following season. Delta Sierras are everywhere.

If guy had been shooting prone he most likely would have been a candidate for a amputation. He was shooting standing and had a shooting glove on and forearm nested the M14 in the glove. It was a big padded glove and not one of the German ones and the glove was shredded and outside of needing to change his underwear and get a stiff one to sip on he was fine.
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Old February 15, 2013, 10:03 PM   #37
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wyobohunter says it seems (from the link Slamfire provided) that the most likely cause of that particular OOB slamfire was single loading a cartridge into the chamber and letting the bolt fly forward. Yikes, never do that!

Garands have been single loaded that way for slow fire, single round shooting since they came into being. 'Twas standard procedures for all the military teams for both the 30 caliber and 7.62 NATO versions. The details of this were to leave about half an inch of the case sticking out of the chamber, then let the bolt fly home.

Regarding fired case sizing tools, wyobohunter, any die type and process combined with poor testing methods and equipment may well prove that any type of die is best.
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Old February 16, 2013, 07:47 AM   #38
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Question on Neck Sizing .308 for M1A

More assumption. This has just gotten silly. You keep believing your story and I'll do my thing. I imagine you'll want the last word so I'll leave it to you. Unless you care to "discuss" the color of the sky? See ya

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Old February 17, 2013, 08:58 AM   #39
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Slamfire is telling you right. I have 3 M1As and I use the RCBS Competition die set, which Full Length resizes. I have never had to use a SB die set. NEVER use Bench Rest primers. The cup is too thin, and can result in a slam fire, due to the floating firing pin. Regular Winchester LR or CCI 200 will work fine. A friend did some accuracy testing with his, and used a chrono. He found that the velocity varied quite a bit more with the Winchester, but there was no difference in accuracy between the 2.
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Old February 17, 2013, 09:18 AM   #40
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Hummer70, I am not argueing with your information, and can only speak from personal experience. My M1A's can shoot sub 1" groups, but they are Super Match versions form Springfield, which according to what Art Luppino told me, is basically the M-21 he built for the Teams. Also, I have a box stock
A3-03 by Remington, that came out of an estate sale. It was prestine when I got it, and I doubt it had ever been fired much. It has a 2 rifleing barrel, and lord only knows how deep the throat is, but it is deep. I have only shot this rifle 2 times. Once in load test and once in an informal bolt rifle military match, all positions from 200 yards, with a possible of 400. I shot a 378, and actually won the match. Going from the M1A to a bolt gun in a position match, and dealing with stripper clips, was kind of unsettling, and I short stroked the bolt twice, in rapid fire. LOL! From a rest, this rifle would shoot sub 1" groups from 100 yards.
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Old February 17, 2013, 03:56 PM   #41
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Chick claims "NEVER use Bench Rest primers. The cup is too thin, and can result in a slam fire, due to the floating firing pin."

Which benchrest ones have you found to be too thin by actual measurements? I don't think there's enough inch-ounce force impact from a floating firing pin in either an M1 or M14/M1A to dimple primers that meet the industry standard for minimum dimple depth for detonation.

All the Winchester, RWS, Remington and Federal rifle primers, both standard and benchrest, have all had cup thicknesses of .027". That's after softening the compound with water, prying out the anvil then digging out the compound and measuring the cup thickness at the bottom. CCI and others may have different thickness. And there are differences in their hardness.

One other thing, Chick, about M14/M1A and M1 accuracy with reloaded ammo. The US Army Reserve Team (Coach CWO4 Billy Atkins) told me some years ago they tried reloading their fired M118, M852 and Federal Gold Medal match brass to cut costs. Never did get reloads to shoot as accurate as new ammo. Their M14NM rebuilds never had their bolt faces squared up; all the fired case heads were way out of square and didn't square up when resized; when high points on case heads aligned with the high point on bolt faces, accuracy was pretty bad. And, like the USN 7.62 NATO Garands which also had unsquared bolt faces, the best of them held in accuracy testing cradles would shoot Federal Gold Medal match ammo inside 4 inches at 600 yards, inside 1/3 inch at 100 yards. None of the service rifle teams got good accuracy with reloaded fired cases from their 30 caliber semiautos.
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Old February 18, 2013, 10:44 AM   #42
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Could you measure:

1.the inside diameter of the Wilson case gage at the bottom with hopefully a digital caliper or hole mic? I have measured three Wilson case gages for .260, 7/08 and 308 and I get measurements of .4725, .474 and .475. Since the chamber dimensions are called for at .471-.473 range and assuming your Wilson gage measures like mine then every fired 308 case in history should fit in your gage with a .474 or .475 base dimension.

Then Slamfire”
“I can measure my Wilson gage and my “homemade gage”, though the “home made gage” was made by Gene Barnett, the barrel maker, with the same reamers he uses in cutting his rifle....”

Then me, I understand the question, I am not big on name dropping, I am big on standards, transfers and verifying. Slamfire checked his Wilson case length gage with a with (an assumed) length standard. He did nothing to determine the diameter of the gage and, that was the question. Turn the case upside down, place the head of the case into the gage.

Here under the pretense ‘we are all learning’. Back to ‘then me’, as my turn to share again information that has been shared before but ignored.
I placed a Wilson case gage on a block of lead, then I placed a fired case into the gage and hammered it into the gage with a round drift (smaller in diameter than the gage). I drove the case into the gage until the case head was well below the top of the gage and additional driving did not drive the case further into the gage. I drove the case back out of the Wilson case gage. Most of the distance into the case was gained when the shoulder of the case was formed to the datum of the die. The shoulder of the case after being driven out was concaved, the concave on the shoulder was a mirror image of the datum in the gage. The case body was a mirror image of the gage body below the top of the gage. Again, the Wilson case gage measures the length of fired and minimum length/diameter cases. There was a poster that was using the Wilson case gage as a chamber gage, not a problem, the problem? He was recommending everyone get a Wilson case gage because it doubled as a chamber gage. He has not spoken to me in a civil manner since.

Chamber gages and tomato stakes: I cut the barrel chamber off of a barrel, not magic, no great name behind the story, but a gage non the less, unlike the Wilson case gage and knock-offs I match case head protrusion with the chamber it matches, think about it, if the gage matches your rifle chamber where is the case head protrusion. THEN! There is always that little bit of class the smith could add to avoid using the thumb nail or pocket rule or better, the straight edge with the companion tool to the press, the feeler gage.
Me and the M1 Garand, every time there was a stop or cease fire/clear your weapons the case ejected had a small dent in it, then there was that floating firing pin and bouncing around in there etc., and I said my rifle is hammer back, how did it get back there?
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Old February 19, 2013, 09:45 AM   #43
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Reloaders by our very programing want to shoot more for less cost which in PC terms is MORE BANG FOR THE BUCK.

Then there are those of us that will scrounge every piece of brass we can find to reload at the range. Bet I have picked up 100,000 empty cases.

Then we have the problem of soft case heads i.e. commercial cases primarily and to some extent some military cases have soft heads. FA 57 30.06 MATCH is one and there was a run of I think it was 72 LC 30.06 with soft heads that was sold by the DCM at Camp Perry as empty brass if I remember correctly.

Soft heads have their primer pockets get loose as can be felt when seating primers and the problem is even more exacerbated by the semi automatic loaders that operate and you cannot "feel" the primers going in.

Now lets say we have a "tired" primer pocket and one of our bretheren with a desire to get more shots down range continues past the ability of the primer pocket dimensions to correctly secure the primer during the cyclic feed of semi auto weapons and.............

Or in other words a round is fired, the bolt of the M1A or M1 or AR comes to the rear and the mainsprings get the bolt going the other way and strikes the head of the new case on the top of the rim typically. With the enclosed bolt heads there is nothing supporting the position of the primer except the fit or snugness of the primer in the pocket.

The primer seated in the loose pocket sets back to where the surface of the primer is ABOVE THE CASE HEAD and does not fall clear or perhaps wedges at a angle. The entire bolt face then becomes the striker which will certainly engage the protruding primer before the bolt rotates into battery and you have a prime combination for a out of battery ignition.

The flash given off by a primer is considerable. Take some primed cases out and chamber and fire them in the dark and you will see flame coming out the muzzle. You will understand immediately there is enough flame generated and the .060" or there about flash hole is large enough to admit a goodly amount of flame setting off the propellant.

As well the set back primer will create a larger area inside the primer pocket and will allow propellant to come down through the flash hole so if there is one piece of 4895 in the primer pocket then the primer is assured not to be reseated leaving the primer surface wedged above the case rim setting the stage for a out of battery ignition. With ball propellant even more can leak out.

Now think about this, every one of us has missed priming a case or a row of cases and the propellent is dumped in the case and you don't realize it till you take case out to seat the bullet and you see propellant in the bottom of the shell holder cavity. 3 or more pieces of 4895 will come though flash hole.

Thus the propellant has already come into the primer cavity just waiting for a chance to do something good or do something bad.

Thus you have a condition that the reloader seats his primers below case head and the nature of the feed mechanism is known for faster case movement, and the above condition is present.

This is why I wanted the information about the cases etc. As I stated above when you are into malfunction investigations you never get the whole story.

Things GOTHIAHB very quickly. The EVIDENCE disappears in the excitement of the moment you are left with not knowing.
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Old February 20, 2013, 11:10 AM   #44
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Quote:
Garands have been single loaded that way for slow fire, single round shooting since they came into being. 'Twas standard procedures for all the military teams for both the 30 caliber and 7.62 NATO versions. The details of this were to leave about half an inch of the case sticking out of the chamber, then let the bolt fly home.
Of your posts that I have read, this is the absolute worst advice that you have given to date.

There are a number of FM’s and TM’s, and they give conflicting direction. The oldest say to put the round in the chamber and let the bolt fly home. Another, and I can’t find it right now, the direction was to let the bolt forward to this position and then left the bolt fly home.


I was unable to copy the picture in the manual, it was in adobe, so I made my own picture.

All good advice, such as using a SLED, the advice in the TM to lower the bolt by an inch, follow one consistent theme: reducing the kinetic energy of the firing pin by slowing the bolt down.


I remember the 2001 Garand Match at Camp Perry. This was the first year they ran out of LC ammunition and issued Federal made 30-06 ammunition.
They issued this ammunition:



On the load command for 200 yard standing slow fire, there were so many slamfires in the morning, a friend said “they like never got the match going”. I heard one in the afternoon session, which I shot, and my hut mate was near the shooter and said the guy’s Garand slamfired in battery. These poor unfortunates were just putting a round in the chamber and letting the bolt fly.

With a tight, long, interference fit round, such as a neck sized round, those slamfires would likely have been out of battery.

Quote:
Quote:
Chick claims "NEVER use Bench Rest primers. The cup is too thin, and can result in a slam fire, due to the floating firing pin."
Which benchrest ones have you found to be too thin by actual measurements? I don't think there's enough inch-ounce force impact from a floating firing pin in either an M1 or M14/M1A to dimple primers that meet the industry standard for minimum dimple depth for detonation
Someone contacted CCI and they don’t recommend the CCI Benchrest primer for M1a’s Garands. The stated reason was a thinner cup. Maybe the cup is actually softer, heck if I know, maybe the priming compound is more sensitive. I have not called, you can, but going in the direction of more sensitive is a bad direction for a gas gun with a free floating firing pin.

This is CCI’s advice: http://www.cci-ammunition.com/defaul...=10&prod_id=30

"Military-style semi-auto rifles seldom have firing pin retraction springs. If care is not used in assembling ammunition, a “slam-fire” can occur before the bolt locks. The military arsenals accomplish this using different techniques and components—including different primer sensitivity specifications—from their commercial counterparts. CCI makes rifle primers for commercial sale that matches military sensitivity specs that reduce the chance of a slam-fire when other factors go out of control*. If you’re reloading for a military semi-auto, look to CCI Military primers.. "


The Army always used the FA34 primer. I found this on page 4-69 of the "Report of the M16 Review Panel Appendix 4 Appendix 4 Ammunition Development Program"

You can find this at http://www.dtic.mil/dtic/index.html.

The Army was having all sorts of issues, slamfires, primer sensitivity, etc, with the early M16’s. The quote from the primer sensitivity section was
Quote:
“Contrary to the requirements for 7.62 mm ammunition, which specifies that the FA34 primer is mandatory, no attempt has been made to standardize on type of primer for 5.56 mm ammunition”.

The #34 primer is a less sensitive primer than commercial primers. You want to use the least sensitive primer you can find in M1a's, Garands, M1 carbines and Mini 14's. Same for AR15's, AR10's. In fact, for any mechanism with a free floating firing pin.

Just feeding rounds from the Garand magazine will leave a pit this large on a primer. Should not take too much imagination that given enough tries something is going to happen.




Quote:
The primer seated in the loose pocket sets back to where the surface of the primer is ABOVE THE CASE HEAD and does not fall clear or perhaps wedges at a angle. The entire bolt face then becomes the striker which will certainly engage the protruding primer before the bolt rotates into battery and you have a prime combination for a out of battery ignition.
What I read into your post is an attempt to steer the discussion back into “only high primers cause slamfires”. I do not agree with this. I have had lots of loose primers with AMERC ammunition in the 45 ACP, primers that were seated on a progressive press, but the crap AMERC brass had loose pockets. The majority of times the primer fell out. I have memories of a number of misfires with AMERC, extracting the round, finding a loose primer, or no primer, finding the primer, putting it back into the case, dropping the round into the chamber, and firing the thing. My experience with loose primers has been malfunctions not slamfires.

CCI has stated that the number one cause of misfires is high primers. CCI states that for for reliable primer ignition the anvil must be firmly seated and the primer cake must be pushed into the anvil.

I do not doubt that that cocked primers or some weird condition could result in a seated anvil and then there is a potential for primer ignition, but it takes work.

If you take mechanical issues, broken firing pin, hammer following, none of which are subtle and are easily diagnosed because they will continue to fire the weapon, if you take these off the table, (and bumpfiring) the primary reason for slamfires is primer sensitivity.

People who have slamfires have difficultly assigning the causes, they don’t know what to look for and are just as likely to assign witchcraft as a cause as anything else.

I have been collecting web accounts of slamfires in the Garand/M1a/M1 Carbine and other rifles. The most reliable are those which people are shooting factory ammunition as factory ammunition is less likely to have high primers than reloads.

I posted a bunch of Garand slamfire accounts in this thread and I think it supports my contention that the primary cause for slamfires (ignoring mechanical issues and bumpfiring) is primer sensitivity.

Loading for Garand:

http://thefiringline.com/forums/show...arand+slamfire
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Old February 20, 2013, 11:28 AM   #45
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I was in no hurry to go distinguished high power and it took me ten years to get it as I shot a gas gun every third match to keep my average in the Master Class as I did not want to get into High Master. I never saw or heard of a slam fire with M14s or M1As during the whole time and we never got any M14 rifles in for catastrophic failure analysis. Whoops forgot, we had one. The boys at Benning welded a op rod guide to a barrel and the barrel let go just short of the welded area.
Ha, ha, you were a High Sandbagger, so did you also wear the tee shirt?

After shooting over a decade of High Power matches at Camp Perry I found a trend: High Master shooters don’t want other HM’s to pull their targets. They don’t want MK, SS, pulling either, so while the HM’s are on the line at Rodriquez, Master Class and Expert shooters are their pitt pigs.

I have commented a number of times that all Master Class shooters at Perry be issued a tee shirt that says

HIGH MASTER
Target puller

By the way, I measured my Wilson and Barnett gages. With your technical background you know that everything has to be calibrated, nothing that is calibrated stays in calibration, and I don’t have NIST gage blocks. Also, measuring to the ten thousandth’s with my equipment, the accuracy of any numbers I produce must be taken as an article of faith.

I used an expanding plug gage exactly at the mouth end and measured the distance of the plug gage with a micrometer.

For the Barnett gage, the distance at the mouth opening the median data set was 0.4735” to 0.474”

For the Wilson gage, the distance at the mouth opening, the median data set was 0.473 to 0.474”
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Old February 21, 2013, 06:21 PM   #46
Bart B.
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Slamfire, the info below was not considered my me to be advice:
Quote:
Garands have been single loaded that way for slow fire, single round shooting since they came into being. 'Twas standard procedures for all the military teams for both the 30 caliber and 7.62 NATO versions. The details of this were to leave about half an inch of the case sticking out of the chamber, then let the bolt fly home.
Just a short history lesson. 'Twas written in past tense; "the way things were years ago." I've no control over how one interprets it purpose. If anyone thinks it is bad advice, then that's fine by me. Then perhaps they won't single-round load Garands that way.
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Old February 21, 2013, 06:52 PM   #47
Slamfire
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Just a short history lesson. 'Twas written in past tense; "the way things were years ago." I've no control over how one interprets it purpose. If anyone thinks it is bad advice, then that's fine by me. Then perhaps they won't single-round load Garands that way.
Sorry if I sounded as too much "Old Testament Fire and Brimstone"

The military ammunition used in those years is basically gone. US military NM and ball ammunition made for the Garand was made by people who understood the rifles operating characteristics and made ammunition with the proper powder, pressures and primers.

Commercial ammunition is not made by people who understand the operating characteristics of Garands and is made by entities only interested in maximizing their profit.

Back in the day, in Government Owned and Government Operated ammunition plants, if the QA inspector rejected a lot, yes he had to prove it was out of spec, but the production manager got yelled at for wasting Government money. Today, if the QA inspector rejects a lot, yes he has to prove it was out of spec, but Corporate calls down, tells the inspector he is costing the company profit, and that if he keeps on rejecting product, he can be replaced.

One has to be more careful and thoughtful when loading Garands with commercial ammunition and primers.

I have heard horseburger is real popular in Europe these days. It comes in a package labeled "Beef burgers".
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Old February 21, 2013, 08:36 PM   #48
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Slamfire, one wasn't more careful and thoughtful when loading Garands with commercial ammunition and primers from Western Cartridge Company, Remington, Federal, Hornady and Winchester ammo in their Garands. There was never any discrimination as to how to load ammo depending on its source on the military teams as far as I know.
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Old February 22, 2013, 11:27 AM   #49
Slamfire
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Slamfire, one wasn't more careful and thoughtful when loading Garands with commercial ammunition and primers from Western Cartridge Company, Remington, Federal, Hornady and Winchester ammo in their Garands. There was never any discrimination as to how to load ammo depending on its source on the military teams as far as I know.
You have seen six or eight rifles that slamfired, you never went in detail about what happened or whether these were in battery or out of battery. Few people have ever seen that many rifles slamfire. But even given all that experience I have only heard you state that anything other than mechanical causes, or high primers cause slamfires.

What is it with the older generations? When will the light go off that primers vary in sensitivity and given a sensitive enough primer, a free floating firing pin will set it off? Telling people to drop the bolt full down on a cartridge increases the chance of a slamfire because the bolt is not slowed down by anything.

The NRA changed the rule about loading the rifle on the stool. Back in the day with bolt rifles and M1a’s you could insert a round in the magazine and rest the rifle butt on your shooting stool. Then the AR15’s replaced M1a’s on the firing line. I used to see AR shooters resting the muzzle of their rifle on the stool, insert a round in the chamber, and letting the bolt fly. Enough posts were put out on the web of shooters whose AR15’s slamfired through the shooting stool, spewing shrapnel everywhere, that that practice is now forbidden.

I would have to look at the rule book, but my recollection they added a rule that if you have an accidental discharge and the round hits within ten feet of the line, you will be evicted from the match.

We have all these pistols with firing pin blocks, military primers that are spec'd to be less sensitive than commercial primers, I have posted lots of accounts of slamfires in Garands with Federal primers (most sensitive primers out there) and it does not make an impression. There are lots of slamfire accounts with other mechanisms, and that still does not make any difference at all.
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Old February 22, 2013, 12:24 PM   #50
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Slamfire, I've only seen one slam fire but have seen cases from 20 or so. Every case had a full, normal indentation in its primer.

There's no rule about accidental discharges empty case distances from the shooter neither the 2012 NRA High Power Rifle Rule Book nor the 2012 CMP Competition Rules that I can find. Their may be local match rules so stating it, but that's up to the Match Director to have them put in the rules for such matches.
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