Full length sizing for accuracy

[deepcore]

Hi

Saw the thread that covered the issue about neck sizing only and (semi) auto
actions.
Basically "don't".

Is there something that can be done with full length sizing (as the only option) that can approximate the consistency a neck sized only case that's been fire-formed to a bolt gun's action?

Thanks

[TXGunNut]

Good question. I personally don't neck-size and don't see the need for it. I consider it a benchrest technique that I'll never see the need for. My latest primary rifle has a pretty tight chamber so full-length sizing doesn't affect it much. I also load for four different 30-06 rifles so FL makes lots of sense for reliability.

[PA-Joe]

Yes you can. You can use you FL sizer to neck size only. Just back it out a few turns. You can also make certain that you do not set the shoulders back more than a 0.001. Both of these options will make certain that there is no slop or free space at the shoulder thereby helping to line up the bullet better with the bore. If the case is sized too small it will move around until it expands to fill the chamber.

[Brian Pfleuger]

You can use a Lee Collet neck sizing die and then a Redding Body/Shoulder die.

[dmazur]

The reason for "don't" is for chambering reliability. If you stray too far into bolt-action reloading techniques, you may have accurate ammo that won't chamber consistently. Or, you could increase the risk of slamfires.

You can determine what your chamber dimensions are for your semi-auto, and then set up your full-length resizing die for -0.002" to -0.003" less than that. This should give you reasonable brass life.

Many service rifle competition shooters report excellent accuracy with full-length resizing, by the way.

[deepcore]

Thanks guys.
Couple of things:

dmazur:
1. I'm assuming I should measure a fired case to determine chamber dimensions specific to my rifle. Where should I take the measurement to determine the minus .002 to .003?

pa-joe
2. When you say set the shoulders back no more than .001..do you mean
the shoulder diameter?

3. Is there a source for (loaded) case check gauges that can be ordered specific to your chamber dimensions?

4. Understanding that single staging reloading is best for accuracy...how far can someone take long range accuracy using a progressive press?

5. Also, another bolt gun vs semi auto item: adjusting overall case length so the bullet just touches the rifling. If that measurement in a semi auto makes the case too long for the magazine do you just stick with the longest length you can get?

Thanks

[steve4102]

Hey deepcore, these are all good questions and I'm sure others will be along to help you out, but in the mean time how about a little more info on your set up. What rifle/cartridge are you loading for?

#1, you measure from the datum line on the shoulder to the base of the case. I use the Stoney Point (Hornady) gauge for this.
http://www.midwayusa.com/viewProduct...tNumber=479704

#2, no the diameter stays the same, you bump or push the shoulder back towards the case head.

#4, Don't have a "progressive", but I don't think accuracy will suffer loading with one as long as things are set up correctly.

#5, load to fit the mag and cycle the action. Loading to the lands is not always the best place for accuracy. Barnes did a study awhile back and found that most rifles have more than one OAL sweet spot, one seated up close and others seated much deeper.
Scroll down to "from the lab".
http://www.barnesbullets.com/resourc...rnes-bullet-n/

[Nnobby45]

Is there something that can be done with full length sizing (as the only option) that can approximate the consistency a neck sized only case that's been fire-formed to a bolt gun's action?

Yes.

Adjust the die so the sizing action stops right where the shoulder joins the neck---just bumping the shoulder slightly, while the rest of the die adequatley sizes the body (not much sizing will occur there, either). If the case was fired (fireformed) in the chamber of the rifle you're loading for, then the amount of sizing will be very little.

You may have to make adustments downward slightly from here, but this is a good place to start.

The idea is to size the case JUST ENOUGH for easy chambering in your rifle.

This is still full length sizing, though some may have a different definition. some feel that FL sizing means resizing as close to factory dimension as possible.

**Remember that full length sizing causes the case to grow bigger (where it's too tight to fit the chamber) just before shoulder contact is made to set it back so it fits. That's where it's all happening, and it's that degree of setback that's so critical.

If you size cases that haven't been fired in your gun, then you just have to adjust the die downward until the case fits the chamber, since starting where neck joins the shoulder won't be reliable---no telling what sized chamber it was fired in. It may be too small already! Or too big.

That's why I like the RCBS Mic Gage to measure cases to let me know just where I'm at compared to my chamber dimensions.

Be careful not to stick the case in the chamber before you get it small enough to fit.

The sizing methods and reason for using them come from P.O. Ackley's Handbook for Shooters and Reloaders--I've used them for years.

[Nnobby45]

Yes you can. You can use you FL sizer to neck size only. Just back it out a few turns. You can also make certain that you do not set the shoulders back more than a 0.001.

I don't think .001 is quite enough. If the elasticity of all the brass was exactly the same, it would work, but I've found that sized brass can easily vary from .0015 to .002, and that you need to size that much to eliminate the variations and prevent some chambering too tight.

Suggest smoking the neck, or using magic marker so you can see the sizing action meet the shoulder and make minor adjustments from there so ALL the cases easily chamber.

However, for those who like a tight fit with some feel, then .001 would probably work. Just that some will be tighter than others.

[PA-Joe]

As noted above, you can measure with one of these:


http://www.midwayusa.com/viewProduct...tNumber=479704

[Unclenick]

PA-joe,

Your link is broken. Here's one: The missing link. It needs to be added that you need a caliper to use this tool with.


Deepcore,

The tool above has inserts that are the diameter of the case shoulder at its measuring datum for the cartridge case you are loading. Datum just means a measuring reference location. If your chambering is .308 or .30-06, then it will be the 0.400" diameter hole that stops at the datum plane location on the case shoulder. If it is a .223 chambering it will be at 0.330" diameter on the shoulder. You put the adapter on your caliper and close the jaws on it and zero the caliper. Open them, insert the case neck into the adapter hole and set the head on the the moving jaw of the caliper. That measurement is the length from the head to the correct diameter at the shoulder (the shoulder datum). That's how it is measured these days. (The military used to go from the head to the shoulder and body line intersect to determine chamber size. Much more awkward to do accurately.)

Once you have that measure, Redding makes sets of competition shell holders you can get that have different thickness. Choosing the one of these that lets your shoulder set back the right amount is helpful because pressure between the sizing die and shell holder that you create during setup helps overcome some of the variance Nobby45 is referring to. I find that, during sizing, if I pause with the case in the die for a count of five to let it relax a little, I get better consistency, too. Rotating it 180 degrees for a second trip into the die and a second count of five helps more. This technique often results in cases 0.001"—0.002" shorter than the usual quick single trip into the sizing die provides.

The sizing die is also going to narrow your cases as you set the shoulder back. This is important to self-loader feed and won't occur in neck sizing-only. That said, a lot of service rifle match shooters do what Peetzakilla suggested. For rounds they will load singly for the slow-fire prone phase of the match, they will use a neck sizing die followed-up by a trip through a body die that doesn't change the neck, but only sets the shoulder back a little to improve fit. That avoids a slam fire, but still lets them take advantage of the precision loading technique. This still does not produce a round that will feed from a magazine reliably. It is strictly for single-loading. If you are shooting VLD shapes at long range, that's fine because they are seated out too long to fit in most magazines anyway.

[deepcore]

Thanks!

Will get on getting the Hornady head space gauge set.

Regarding my set-up: been reloading pistol only but taking the plunge and want to start reloading 308. Usually use bulk ammo for my Springfield HK-91 clone (flutted chamber, and whether or not you can reload that brass is another discussion) and factory ammo for my Winchester 70 308 cal with short but heavy bull barrel. Have a Dillon 650 (and the $30 Lee single stage).
Plus in the middle of a 308 AR build (waiting on the paperwork of an Iron Ridge lower and will use it with a DPMS upper with a 24 in. bull barrel)

So will be reloading for bolt and semi auto in 308 for long range.

[Nnobby45]

You can determine what your chamber dimensions are for your semi-auto, and then set up your full-length resizing die for -0.002" to -0.003" less than that. This should give you reasonable brass life.

That's a good, simple analysis.

With the RCBS Mic Gage, I take an average of several fired cases. The cases should be twice or three times fired, to remove the springiness of the brass. Especially if you send your brass in for making a custom die.


The gage is a HEADSPACE gage with a base and a screw on cap with micrometer readings. It's really just a reference. Once you know what your chamber measures on the gage, then size your brass as described above.

It also comes with a seperate cap and base for measuring bullets so you can seat different bullets, with different ogives, the same distance from the lands.


Other gages work on the same principle. No worrying about datum lines, or the technical stuff. Just measures the shoulder for headspace on a basis that compares sized cases (or cases fired in another gun).

I have a rifle built with a Krieger barrel with minimum chamber and it Mics at minus .001 on my gage. Another gage could be different.

A friends rifle, for example, Mics at a plus .005. That's .006 difference and you can see a problem if ammo sized to fit my minum chamber was fired in his maximum chamber. Headspace would be .008 or so.

If I sized for a safe .005 headspace for my rifle, then that would be .010 to .011 headspace his big chamber. If I loaded for a maximum .007 headspace for my rifle, that would be a potentially catistrophic .013 when fired in the maximum chamber. Not just shorter brass life at stake.

Not trying to be too technical or impress folks with how much I know, but new handloaders might be saved some grief if they knew more about headspace and how critical it is.


At the very least, get a simple go-no- go headspace gage, like the Wilson. A good Mic gage from RCBS would be better, as would some of the other measuring tools some have mentioned.

[Unclenick]

Nobby45,

I have a couple RCBS Precision Mics, and found I needed to put a GO gauge in and calibrate them. Both are off absoluee by a couple thousandths based on that.

I can give you a really extreme example of excess headspace. I was at the range one day and a fellow a couple of benches down had just arrived to sight in a borrowed rifle for hunting season. After his first shot, he called over to me and asked me if I thought his fired case looked normal? The fired .308 case had no neck. It terminated in a rounded shoulder all the way forward. I picked up the rifle and showed him where the chambering was stamped on the barrel. It said .30-06. The thing had fired and even hit the paper IIRC, but low. No damage to gun or shooter, though.

Take a look at Hatcher's Notebook's Chapter 10 on headspace. Keep in mind he references the old military measure of headspace, which was from the case head to the corner where the shoulder starts. Nowadays we use the SAAMI method of measuring to a shoulder datum.

Here I need to correct myself from my last post. The 0.400" wide datum is only for .308 Winchester. The .30-06 uses a 0.375" datum in the drawing I have, which I had forgotten. In any event, all of Hatcher's headspace numbers in that chapter for the .30-06 will be .1088" shorter than the SAAMI measure that an RCBS Precision Mic or the above caliper adapter uses.

Keeping the above in mind, you'll find Hatcher describes an experiment in which he used a special reamer to lengthen the headspace in a test gun to see where it became dangerous. He got all the way out to something like 0.050" over maximum headspace and still didn't suffer any head separations firing new military cartridges. Cases won't be so forgiving after you've reloaded them a few times, though. The pressure ring will be thinned out, then. Eventually the oversize chamber will get you into trouble with head separations in your reloads and you'll need a broken case extractor. Hatcher has a good drawing of this separation coming about in stages due to excess headspace. It is all in the same chapter.

So, excess headspace is probably almost never a problem for new cartridges, but you want to watch for the development of a pressure ring in cases you'll reload. If you miss one, this kind of head separation is not a catastrophic failure. You just need a way to extract the upper half of the case left in the chamber. Keeping a stuck case extractor in your kit is a perfectly good practice. I suppose, if it happened frequently, the chamber would develop a gas cut ring in the separation area and eventually need setback and re-cutting or a new barrel. Seems pretty unlikely if you keep an eye on your brass.

[zeke]

Uncle Nick-thanks for the info on the Redding comp shell holders.

deepcore-would advise you keep any brass from the hk-91 clone seperate. After reloading brass fired in a hk-91, the action type seriously stretched the brass. While it can be done, it was not worth the aggravation, and would not rely on the brass for repeated reloading.

[F. Guffey]

Nick, it happens too many times, the 308 W will chamber in a 30/06 with resistance, the shoulder case body juncture is .011 thousands larger in diameter than the 30/06 when measured from the case head to the same point, meaning the 308 W is sized down at the shoulder when chambered, there are those that claim they can chamber ia 308 W without resistance and will never consider their chamber is stretched as in expanded without spring back?, they also believe recovery, memory and or spring bck is limited to the case when fired.

That is the reason I am not a fan of chambering with resistance, like a pass in football, 4 things can happen, 3 are bad. Sighting in a rifle for a friend? It happens too many times, A very upset shooter had planed his course, everybody involved was going to pay, the shooter could not open the rifle and had no choice but to seek help from a North Texas gunsmith, not the nice one, the other one. the one that allows the other person to talk himself into a hole. Long story, after the case was removed and what was left of the evidence was examined it was discovered the shooter also purchased the ammo for sighting, he purchased 308 W for a 25/06 and shot it. I can only guess how the bullet got out of the barrel, others believe the bullet was swaged down and came out twice as long as it went in, I believe the bullet turned inside out and came out in pieces. To make sure the shooter did not have two boxes of ammo on the bench one of the questions was asked "Was this first or second shot"

As you did the smith identified the marking on the barrel and through magnification identified the case head that was fired. The smith after listening to three hours of "I am going to sue everyone" when finished he ask the shooter "Now that we know the rifle and or ammo was not at fault are you going thank them for building a rifle that was strong enough to forgive you for your mistake"? I doubt the owner of the rifle was informed of the mistake, the rifle was checked and cleaned up and we know the shooter did not return with an update the rifle was a Howa.

Back to the head space and case head separation, the 8mm57 has been fired in the 8mm06, that is .127 (+/- a very few) difference in head space, when cases is ejected it come out looking like 8mm06 with short neck, I have no ideal why Hatcher did not get his expected results unless he ommitted the time factor, his test, in my opinion was flawed, his case did not lock to the chamber until the case expanded to fill the chamber, meaning expansion of the case body was not limited to the area between the case head and case body, the expansion of the case in his experiment was spread out through the length of the case from the case head to the newely developed shoulder, part of the shoulder in his experiment was erased and became part of the case body, part of the neck became part of the shoulder,. so like all the reloaders I know he basically fired to form, as opposed to form first then fire, like me.

Had Hatcher marked the test cases with hash marks in thousands he would have would have been able to determine he was fire forming/head spacing off the extractor, who knows? the marks on the case could have been know as HATCHER MARKS, something like the HATCHER HOLE. As I have asked about stretch and flow, If the case stretches down the chamber, where are the skid marks? What evidence do we have that brass flows?

F. Guffey

[Unclenick]

I'm guessing that like the .308 in the bolt gun I saw, Hatcher's gun eventually headspaced on the extractor hook as he reamed the chamber progressively deeper for each test, and that set the limit to how far back the head had to back up to stretch the pressure ring out. Once he got the chamber long enough to hit that limit, all further case expansion was, as you suggest, the shoulder blowing forward by drawing on neck brass. Still, its good to know extractor headspacing is tight enough to prevent a separation with new brass.

I found this article by a fellow who accidentally fired some .308 in his .30-06 Garand at the National Matches in 1964. If you scroll down it includes a photo of the case. The self-loaders, of course, don't let you feel whether the case is going in a little on the firm side or not.

Nick

[wncchester]

"...new handloaders might be saved some grief if they knew more about headspace and how critical it is."

Actual headspace is critical to a gunsmith or company doing the chambering so factory (SAAMI Spec.) ammo will properly fit. Thus the makers need a conventional headspace gage. But, for handloaders, such a gage is virtually usless and the specific chamber headspace doesn't matter at all.

Striving to return cases to meet SAAMI spec insures that most reloaded ammo will be unnecessarly short, head-to-shoulder (excess headspace), ammo. And that insures excessive stretching with each firing.

Reloaders need an understanding of how to make their resized cases fit their chamber and that's all they need. Only something like the Hornady or Sinclair case tools and a precision caliper, or an RCBS Precision Case Mic, or an Innovative Technoligies cartridge case gage can tell them how they need to resize their fired cases for a proper fit.

I size my cases to fit my rifles and I get little to no stretching that needs trimming until they fail with a neck split. Or, with occasional neck annealing, they will last for 20+ full power cycles, again with little or no trimming. And I have NO IDEA of what the actual "headspace" is for any of them!

[F. Guffey]

Nick, go green, use the companion tool to the press, the feeler gage, if light is allowed to pass between the top of the shell holder and bottom of the die when the ram is up (cammed, jammed or wedged over) there is a gap, because of focal points/diopters it would be difficult to measure the width of the light beam without guesstimates, not often but when I wonder what is happening when sizing a case leaves me with unpredictable results, I use a feeler gage.

After determining the case is whipping my press and I decide to make an adjustment as in an additional 1/4 turn, 1/2 turn etc., after making the adjustment and sizing the case, before lowering the ram, I can check progress with the feeler gage.

If full length sizing is determined by lowering the die down to the shell holder with the slack removed between the threads and the flex is removed from the press when using a shell holder with a deck height of .125 and a standard full length sizer die I expect a full length sized cases, but when sizing cases for long chambers I compensate for the additional length with a feeler gage, again, I have one rifle with .016 thousands head space, I size cases for that rifle with a .014 thousands gap between the top of the shell holder and bottom of the die.

It goes to 'has weight and takes up space' if the die is not getting down to the shell holder when full length sizing the amount of or lack of the press to size the case results in a case that is full length sized plus the gap, the failure of the press to size the case could be traced to bad habits, a reloader should have a standard (new unfired case) for comparison as when determining the difference between sizing cases that have been fired 5 times with a case that has been fired zero, once, twice etc.. and I do not buy that part where the case is fired 5 times THEN it is necessary to start over by full length sizing because the case is full grown?? How can a reloader start over, the case has been fired 5 times, bad habit, bad advise?

Bad habit, a reloader purchases new cases, them fires everyone of them, before firing all of the cases chambered, the reloader is left with no clue as to the dimensions of a full length, minimum size case.

F. Guffey

[F. Guffey]

"Actual head space is critical to a gunsmith or company doing the chambering so factory (SAAMI Spec.) ammo will properly fit. Thus the makers need a conventional head space gage. But, for hand loaders, such a gage is virtually useless and the specific chamber head space doesn't matter at all"



There are those that purchase three head space gages, go, no and beyond for $60.00 +, why that is cheaper than learning to use a press is beyond me, and , I have said I can can convert a head space gage to read head space in thousands from .005 to infinity, not knowing, I understand, not wanting to know goes with spending $60.00 before taking the time to learn to use the press.


"virtually useless" ?, A head space gage is a standard, it is a transfer, two terms unknown to forum reloaders, If I had a head space gage (store bought) I would use it as a set-up tool, I would use it to determine if a misinformed (previous owner) reloader ground the bottom of a die to compensate for the lack of skill with the press, the shell holder when manufactured had a deck height of .125 and checked can be measured with a depth gage/micrometer.



Before I posted misinformation about the merits of one die over the other I would use a standard/transfer/head space gage and compare. Full length sizing is sizing a case to minimum length, minimum length? is over the counter, store bought ammo, factory, commercial ammo, the ammo that is sized to fit all of SAMMYS chambers, the problem,? I have two chambers that are Sammys, the rest are SAMMYS + or ++ and a few I cut that are SAMMYS -.



To use the head space gage as a standard/transfer, remove the the primer punch/neck expander ball assembly from the die, install the head space gage in the shell holder and raise the ram, then lower the die down to the head space gage, once the die contacts the gage STOP, secure the lock ring, lower the ram, remove the gage then raise the ram again, in the perfect world the light beam passing between the top of the shell holder and bottom of the die for the 30/06 set up will be visible, if measured with a feeler gage the gap will be .005, nice to know?? Too much trouble? Or worst, do not want to know, again not knowing is OK, but if the gap is less than .005 the die and shell holder in that press does not have the ability to full length size a case to SAMMYS specification, if the gap is greater than .005 cases after sizing could present resistance to bolt closing,.



So to turn a tool into something that is VIRTUALLY USELESS put it into the hands of someone that is clueless and does not want to know. and I disagree with the recommendations of purchasing another tool before the user learns more about the tools the tools they are using.



Again, looking for parts and bargains I was in a store that has both, the owner/smith turned a customer, he informed the owner of one very fine rifle chambered in an unusual chamber he could not check head space on that chamber because he did not have a gage. I did not get involved. Then the customer left, I then informed the owner/smith I could check head space in thousands as many as three different ways with out a head space gage (no, go or beyond), he then ask "HOW" the man is good, he did not get that way by doing all the talking, he listens like Nick and Dick Culver.



I have spent time on the phone with Dick Culver, there are a few stories that are repeated over and over, when he says "I was there" he makes the truth more interesting than legend. ( from the story) 'THE MAN WHO SHOT LIBERTY VALENCE' when truth gets into the way of legend, we go with legend every time.



F. Guffey

[F. Guffey]

It has not been that long ago the DATUM was described in lofty terms like 'the datum line',. the person providing the information did not understand what or where it was, that lead to most believing it was a deep/dark secret that was to be know only to the few. from the beginning the datum was round a hole, like a bass boat being described as a hole in the lake fisherman pour money into, the tools that are sold and called head space gages are in reality case comparators.

I have described trips to a gun show that resulted in me finding a box of datums, I would say "DATUMS"! the seller on one side of the table and those around me have reacted with, "WHERE!" I DON' SEE ONE! AND THE BEST RESPONSE "What does a datum look like"??, for me a datum is anything with a hole in it, I have absolutely no ideal why there is an assistance on using .375 for the 30/06 or .400 for the the 308 W, a hole that allows the case to fall into is too large and a hole that is too small for the neck is too small. I make up my own datums, they are cheap, I have drills and straight reamers, when comparing the length of a case from the shoulder to the head of the case use the same hole for the before and after measurement, and holes are available for purchase.

Finding a DATUM of .375 is not difficult, for those tha can drill a straight hole with a 3/8 drill, when finished the hole is .375 + or - very few.

F. Guffey

[F. Guffey]

insistence's

sorry about that,

F. Guffey

[Unclenick]

Datum is the singular of data. It is the first point in a series of data from which the others proceed. These could be points of information or a series of measurements or even reasoning steps starting from a known sitrep as the datum. Datum describes the starting point in all these examples.

In machinery and other non-computational devices, a datum is usually a point or a line or a plane or a combination of these (e.g., a particular point on a particular plane) that is used as the reference for measuring and figuring the rest of the machine. The single reference is used to prevent cumulative error that would could occur if you referenced angles or planes or lengths to preceding figured parts instead of referencing them all directly to the original datum.

In chambers and cartridge cases made to SAAMI specifications, the datum is defined as any point on a circle of a particular diameter on the exterior of the case or the interior of the chamber and lying on a plane perpendicular to the axis of the case or chamber. Why is it some particular diameter? Because that is SAAMI specified as the only diameter that works with their specified chamber and cartridge headspace lengths.

It has to be remembered that SAAMI is an organization of manufacturers, not reloaders. SAAMI's members need a way to know they are manufacturing chambers and cartridges that are compatible with one another. Even though the ammo maker and chamber maker may never see each others work, their products still have to fit together. If the datum were not some particular diameter, then cartridge and chamber headspace numbers given in the SAAMI drawings would not work.

For example, the SAAMI drawings for the .30-06 use a headspace datum that is a 0.375" diameter circle on the shoulder. The headspace datum diameter is the only dimension that is always the same for both case and chamber. All other dimensions are different so the case will be a little smaller than the chamber, guaranteeing it will fit in. The SAAMI drawing has the bottom surface of the case head 2.0519"–2.0526" from that one particular 0.375" diameter location at the shoulder. If an ammo manufacturer arbitrarily switched to a 0.4000" diameter datum, as is specified for the .308 Winchester, then used the same 2.0519"–2.0526" length from the datum to the breech end of the head, his cartridge cases would come out 0.0387"–0.0394" too long for chambers made using a 0.375" diameter datum. This is because a wider circle meets the shoulder taper nearer to the head.

The shoulder datum was not always used with bottleneck rimless and beltless cases. The military long employed the distance from the casehead or breech face to the intersect of the shoulder and side of the case or chamber. If you look at .30-06 headspace numbers in Hatcher's Notebook, for example, they are shorter than the SAAMI numbers because they are measured to that shoulder and side intersect. The Garand blueprints also use that system of measure. The problem with it is the chamber and new case are not the same diameter at their respective shoulder and side intersects. The chamber is a minimum of 0.0015" wider. Thus, a case, being smaller in diameter, can have the same headspace number as the chamber when figured that way, but when you put it in the chamber it will actually come to rest a little bit forward of sharing the same plane either at the shoulder or the breech.

The SAAMI system solves that problem. By using a datum on the shoulder that is shared by the chamber and case, it avoids any location difference.

The handloader is another animal from a manufacturer. Typically the handloader has his case and gun compatibility established by fireforming. Once he has that, he is interested in differences rather than absolute headspace numbers like SAAMI's. You want to know how much the sizing die pushed the shoulder back from its fireformed size? You want to know how much bigger your case headspace is than a new case. You want to know how much bigger your fireformed case is than a chamber GO gauge, thus to indirectly judge your chamber headspace.

For those purposes any random intersection of a hole and a case shoulder will work as long as it's not too close to the shoulder corners where the radius might not be 100% consistent. Most any close-enough hole through a spacer or bronze Oilite bushing or other odds and ends you might get from the local hardware store may be used for these comparative measures with your caliper. It just needs to be longer than the case neck and for the hole to be square with the ends. Just slip the part over the case neck and measure the combined length. You can even zero it at that length. Then you can easily find how many thousandths of difference there are to any other case or gauge.

[deepcore]

UncleNick,
As I try to assimilate all this info....regarding the Redding shell holders you mention: (dumb question maybe) why adjust at the shell holder and not at the die on top?
Thanks for everyone's input.

[dmazur]

I think I can answer the last question, though UncleNick can elaborate as needed -

The idea is to maintain uniform shellholder to die pressure to remove "flex" in the press, which can result in more consistent results even though you are varying the effective distance the case moves in the die.

Some advocate machining off the bottom of the die to achieve this, but this has the disadvantages of 1) permanently altering the die and 2) doesn't maintain uniform pressure between the shellholder and the bottom of the die as you adjust the die. (Also, it's hard to machine it off square if you don't have the correct tools...)

Here's what they look like -

http://www.redding-reloading.com/onl...ellholder-sets