M1 Garand shoulder setback, 0.010" too much for a one time firing?

[tjd308]

I know I'll catch hell for not checking from the get go and loading 100 rounds and then realizing my mistake, but admittedly I made an error when full length resizing my brass and set the shoulder back too far and now there is between 0.009 and 0.010" of difference in the shoulder of a fired case and the brass I reformed. This is for an M1 Garand using mil-surplus Greek HXP brass (30-06 obviously). I know that the standard most use for bolt guns is either to fire form or leave 0.001"-0.002" but autoloaders should be closer to 0.004" to ensure proper chambering.

• My main question is: Is it safe to shoot this brass this one time to get it back to fire formed size and set my dies properly for the next round of resizing or if I have an unsafe headspace situation that's either dangerous to me or the rifle? Basically will I just be unnecessarily working the brass too much this one time but will be fine or it's not safe and I should just discard the brass?

Also, I've been using a Hornady headspace gauge using a comparator to see how far the shoulder is set back compared to a fired case. The measurements I get (even on other rounds like a non-fired factory case, fire formed, etc) pretty much all come up below SAAMI spec minimum. From what I've learned, this gauge is meant for comparison purposes only and something like the RCBS precision mic is needed to accurately gauge the distance from the case head to proper datum line on the shoulder (and that the measurements tend to read short for everyone due to the design w/ the beveled soft aluminum edge). The SAAMI min-max difference is 0.007" if I'm reading the SAAMI schematic correctly, but again, the comparator style gauge I'm using makes it seem like I'm well below SAAMI and I'm well below the min (could be in....not sure).

• Do I even need to worry about SAAMI spec or is measuring relative to a fire formed case all I should worry about? I assume that if I'm using that brass only in the one rifle then it doesn't matter, but if I wanted to make a round that would fit in virtually any chamber that I should then ensure it's inside of the SAAMI min-max, no?

Sorry for such a long set of questions. I've been hand loading for about two years now and am beyond novice status, but don't want to get careless and do something stupid. I know that excessive an headspace situation (or brass that's out of spec at the shoulder...similar effect) isn't something to be taken lightly. I'd hate to jeopardize my rifle or myself over $50 worth of brass that I should maybe just discarded.

Fire formed measurement:


Full-length resized measurement:


30-06 Springfield SAAMI specs:

 

[Laphroaig]

First, I don't think your brass poses any danger if you load them and fire.

I don't have a comparator. I do load for about 6 or 7 30-06 rifles with the same die setting, including 2 Garands, and have not had a single problem. That is just touching the shell holder to the bottom of the die on the upstroke, using regular RCBS dies. If you followed your die instructions you should be loading SAAMI spec ammo, unless your dies are defective or you are doing a super hard cam-over.

As far as optimizing the sizing depth per a rifles chamber, I don't know if that is truly necessary for most uses. I'd say my brass lasts 10+ reloads if the primer pockets don't get loose first, which they rarely do.

 

[Walkalong]

I did that with some .222 Mag brass. I loaded some long, heavy bullets, jammed them into the lands, and fired them, hoping to keep the brass back and limit stretching. It seemed to work OK. But yours are already loaded and are for a Garand.

.010 is going to cause some stretching, no doubt, but I don't think they will separate on one firing. Several firings, yes. Then next time limit it to .004/.005.

I set up my .30-06 sizer so the brass fit my Wilson case gauge. I did not measure how much I moved the shoulders. It was also for a Garand, but I don't shoot it much and am definitely not a Garand expert.

 

[MEHavey]

Naaaaawww. It'll just blow the shoulder forward as though you were fire-forming it.
(This time)


postscript: I'm very surprised that any standard die was able to set the should that far back.

 

[243winxb]

Take 3 fired factory ammo brass and measure each one.. Place each back into the chamber, making sure the action locks when the bolt slams on it.
Has chambering the fired brass set the shoulder back more?

 

[Bart B.]

What load are you using?

I suggest you don't fire those eases. I think you're setting fired case shoulders way too far. .003" is plenty for Garands. And your readings are not what they should be.

First thing I would do is zero your Hornady gauge on a 30-06 GO headspace gauge; that's 2.0452" minimum. Next, compare that zero setting to case headspace of fired and resized ones then calculate the cases real headspace numbers.

Your gauge measuring datum is a couple thousandths below their flat ends where you probably zeroed your caliper at. I think that's why your numbers are a few thousandths short of what case dimensions really are.

Pull the bullet, save the powder then back the die up about 1/10th turn. Lightly lube that case then full length size it. See if that moved the case shoulder forearm about .0062 to .007 inch. If so, see how it chambers. It should be 3 to 4,thousandths less than fired case headspace. If not, adjust the die a tiny bit then try again with another case.

 

[tjd308]

What load are you using?

I suggest you don't fire those eases. I think you're setting fired case shoulders way too far. .003" is plenty for Garands. And your readings are not what they should be.

First thing I would do is zero your Hornady gauge on a 30-06 GO headspace gauge; that's 2.0452" minimum. Next, compare that zero setting to case headspace of fired and resized ones then calculate the cases real headspace numbers.

Your gauge measuring datum is a couple thousandths below their flat ends where you probably zeroed your caliper at. I think that's why your numbers are a few thousandths short of what case dimensions really are.

Pull the bullet, save the powder then back the die up about 1/10th turn. Lightly lube that case then full length size it. See if that moved the case shoulder forearm about .0062 to .007 inch. If so, see how it chambers. It should be 3 to 4,thousandths less than fired case headspace. If not, adjust the die a tiny bit then try again with another case.

Thanks for the advice Bart. Maybe I'm wrong, but the full length sizing die won't "pull" the shoulder back out will it? Fire forming by shooting in the rifle's chamber is the only way to do that, right? I should note that I actually did not seat primers, charge, and load bullets....so I have just the improperly sized cases sitting here and just running back through the dies would be easy if that worked.

 

[tjd308]

Naaaaawww. It'll just blow the shoulder forward as though you were fire-forming it.
(This time)


postscript: I'm very surprised that any standard die was able to set the should that far back.

I am surprised it set the shoulder back that far as well. I'm using an RCBS full length sizing die that was screwed down until it touched the shell holder, and then went the additional 1/8 to 1/4 turn that the directions call for. This is clearly where I went wrong because I must have gone over 1/4 by a bit. I think the instructions should specify that you should measure your case and adjust the die to suit and not just to arbitrarily screw it in 1/8-1/4 since that would yield a decent range in shoulder setback and thus put some in a situation I'm in. I called RCBS customer service and they said I was doing it properly and kind of acknowledged the instructions were a bit vague. I know for the experienced this is common sense, but they ought to write them so they're dummy proof. Seems like a potential legal liability to me, but whatever. I'm the idiot here as I should have known better.

 

[243winxb]

If actions open a little to soon, the head to datum measurement on fired brass can be longer then the actual chamber.

 

[Bart B.]

Maybe I'm wrong, but the full length sizing die won't "pull" the shoulder back out will it? Fire forming by shooting in the rifle's chamber is the only way to do that, right?

The old method of partial full length sizing fired cases such that only part of the case neck's sized always squishes the shoulder forward as the body's diameter gets smaller in the die. That body diameter will go back to almost what it was and the case shoulder's now further from the case head. How much depends on case and die diameters involved.

Try it measuring everything.

I think the instructions should specify that you should measure your case and adjust the die to suit and not just to arbitrarily screw it in 1/8-1/4 since that would yield a decent range in shoulder setback and thus put some in a situation I'm in

Best words I've seen in a long time. Note the die twists about 1/10th inch on its circumference to change its position up or down about .002". That's because it's 14 threads per inch are about .072" apart. 1/14=~.072.

Get some labels to put on the die lock rings to help adjust the die precisely. See post 9 in:

https://www.thehighroad.org/index.php?threads/headspace.815278/#post-10440532

 

[Bart B.]

If actions open a little to soon, the head to datum measurement on fired brass can be longer then the actual chamber.

I don't understand how that can happen because bullets are several feet out the Garand's muzzle when the op rod twists the bolt counter clockwise to start case ejection.

 

[tjd308]

The old method of partial full length sizing fired cases such that only part of the case neck's sized always squishes the shoulder forward as the body's diameter gets smaller in the die. That body diameter will go back to almost what it was and the case shoulder's now further from the case head. How much depends on case and die diameters involved.

Try it measuring everything.

Best words I've seen in a long time. Note the die twists about 1/10th inch on its circumference to change its position up or down about .002". That's because it's 14 threads per inch are about .072" apart. 1/14=~.072.

Get some labels to put on the die lock rings to help adjust the die precisely. See post 9 in:

https://www.thehighroad.org/index.php?threads/headspace.815278/#post-10440532

Thanks Bart. Very helpful. I've heard of the 0.002" per 1/10 recently in my research. Noted.

What do you think about the response I received to this same question on a different forum. It makes a lot of sense to me:
Use that SAAMI drawing and a little basic arithmetic to see that the acceptable "headspace" difference between a minimum cartridge and a maximum chamber is .0131". So why are you worrying about .010" difference between your fired case (reflecting the chamber dimension) and your sized cartridge cases?

As you already know, .010" axial play between cartridge and chamber isn't ideal for maximum case longevity. But it hardly represents a hazardous condition.

.........so basically his logic says that worst case scenario with a short SAAMI speced shoulder on the case and a long SAAMI speced chamber headspace you'd be at a pretty long distance of 0.013". I'm at 0.010". With that logic I'm okay. No?

 

[MEHavey]

I know for the experienced this is common sense, but they ought to write them so they're dummy proof.

Before we go too far in that direction ,
What does your comparator measure using unfired Greek and/or Commercial ammunition?

 

[Laphroaig]

I set up my .30-06 sizer so the brass fit my Wilson case gauge.

That's the best advice given so far. I'd buy one if you don't already have one, and adjust your dies accordingly.

 

[Bart B.]

I set up my .30-06 sizer so the brass fit my Wilson case gauge.

That only insures the case is the right size to fit that gauge. The case may be too short in headspace which causes head clearance in the rifle barrel chamber to possibly be way too much. Cases should be sized for the chamber they'll be used in for safety, long life and accuracy.

For example, if the case head is at the low step in a Wilson gauge (about SAAMI minimum case headspace) and the barrel chamber's headspace is right at maximum, there can be .010" head clearance on that case in the chamber. That's the space between bolt face and case head when the round's fired. That ends up with excessive case stretching when fired which, over several times, leads to case head separation.

If fired cases from that chamber have their headspace reduced only .003" by proper sizing die setting, case life will be many reloads and head separation will not be a problem. This is how dozens of reloads per 30-06 case can be done. That'll never happen when shoulders are set back any more.

As you already know, .010" axial play between cartridge and chamber isn't ideal for maximum case longevity. But it hardly represents a hazardous condition.

No, I don't know that about it hardly representing a hazardous condition. In fact, it is very much a hazardous condition as stated above. Except when a new case is fired in such chambers because that's the first time the case stretches. After that case is resized back to its original headspace, or more which can happen, then the incipient head separation process starts.

 

[MEHavey]

That only insures the case is the right size to fit that gauge.

Took the words outta my mouth .
There are three "standards" of baseline comparator measure:

- Commercial and/or unfired military (You'll be at SAAMI mins, or pretty close)
- A GO gauge (again, SAAMI Mins)
- Fired brass, but with the Gas plug OUT so as to prevent ejection stresses/strains (akin to bolt action baseline)

........and then the Gold Standard:

- Fired and ejected brass, graaaadully resized so that it's elongated to the point the bolt won't close -- then graaaadully resized more until the bolt just closes.




postscriptum: You can't set-&-forget a sizing die. Every session/every brass manufacturer/every brass-firing lot is different. Keep the comparator handy each time you start, and "double-tap" at the top of the upstroke for best uniformity.

 

[Laphroaig]

This is how dozens of reloads per 30-06 case can be done

Personally I start to get nervous after about 10 reloads. Many necks crack before then anyway, unless you anneal frequently. I guess if 30-06 brass was that rare I'd go through the trouble of adjusting my sizing die for each rifle I load for. But no thanks

 

[kingmt]

The directions are dummy proof as long as your using the same brand die & shell plate. It will make brass to spec as long as nether of these are out spec(defective). The directions have you closing the shell holder against the die & even if the die is turned a few thousandths up or down it won't matter because that is absorb in flex of the press like a spring. Your turning it down another 1/4 turn to insure your spring is tight enough to keep the shell plate against the die.

A comparator can't measure anything by itself. That's why it's called what it is. It compares two objects & tells you the difference. You need a standard to set it before you can use it to measure.

If you want to know exactly how much clearance you have then you need to take that fired case & start with the die off the shell plate & keep adjusting it down in small amounts until it bumps the shoulder back enough to where you think the chamber is closing then put a primer in it to insure it will fire & the bolt will open. This will create you a standard for your chamber. If you set 0 on this standard it will tell you how much to long or -readings will give you your clearance. Other then that your just guessing they have to much clearance. I'm betting you made factory spec ammo by using the die instructions.

 

[Bart B.]

Personally I start to get nervous after about 10 reloads.

People have got dozens of reloads in both 30-06 and 308 Win cases minimally sized setting fired case shoulder back a couple thousandths in gelded full length sizing dies (those without balls) that work neck brass half as much as standard dies. I got 47 and a friend got 56 before we ran out of powder in our tests. No annealing whatsoever. His shot all bullets into a dime size group at 100 yards as tested in a machine rest.

There's no secret; for bolt guns, use a FL die whose neck's opened up to .002" smaller than a loaded round's neck diameter as it holds the bullet used. Then set fired case shoulders back .002". If you use Redding's competition she'll holders, you may be able to set 'em back only .001". Set gas gun shoulders back another .001".

 

[RussellC]

This, or something similar should be a "How much am I moving shoulder/effect on case life" sticky!

I reloaded .223 for a year before I realized how important it is, fortunately I bought sufficient brass that is has only been reloaded once, and all of those have functioned through ARs just fine. (Mixed headstamps) I then acquired a few thousand LC, which I am doing much better with. I want to have a thorough working knowledge and ability before going to .308.

All my info and equipment suggestions came from right here! LE Wilson case gauge and LE Wilson case depth micrometer, Sheridan case gauge , and RCBS headspace comparator to aid with this minimum shoulder moving business.
Russellc

 

[Reloadron]

First thing I would do is zero your Hornady gauge on a 30-06 GO headspace gauge; that's 2.0452" minimum. Next, compare that zero setting to case headspace of fired and resized ones then calculate the cases real headspace numbers.

That is where I would start. A Forster Headspace No-Go Gauge 30-06 Springfield, 25-06 Remington, 270 Winchester, 8mm-06 Springfield, 338-06 A-Square, 35 Whelen can be had for about $30. Forrester, Clymer, PTG (Pacific Tool & Gauge) any of them will do just fine. I have Forrester and Clymer sets and the Go gauges are 2.049". Take the gauge as Bart suggest and measure it using your Hornady Lock-N-Load Headspace gauge using the 0.375" bushing. Note that number since it will be a reference. Doing this my gauge reads 2.047". You will then see the error in your Hornady L-N-L gauge. Mine with this bushing is -0.002". If I measure a fired case from my Garand that case, before sizing will be pretty close to my actual chamber headspace. In my case I would add 0.002 " to my measured reading and figure maybe another 0.001" allowing for shrinkage on my fired case. While not ideal it will give you a reasonably good ball park figure. The idea behind using an actual headspace gauge is you will have a "known" dimensional value to work with. Actually rather than a Go gauge, if only buying one to get a good reference I would buy the NoGo (2.055") strip your bolt down and see if the bolt closes on the NoGo. May as well get a handle on if your chamber is greater than a standard NoGo. A short but good read can be found here: RIMLESS GAUGES FOR SHOULDERED CHAMBERS in the Clymer catalog. The Go and Field limits are pretty much set by SAAMI while the NoGo point is often set by the gauge manufacturer. Forrester and Clymer add 0.006" to the Go dimension.

I am also surprised the resizing die was able to move the case back 0.010". Generally when I set up my everyday RCBS 30-06 sizing die 2.048" - 2.049" is where they all end up and to set a case back 0.010" it would have to have been fired in an awful long headspace chamber.

Ron

 

[Walkalong]

That only insures the case is the right size to fit that gauge. The case may be too short in headspace which causes head clearance in the rifle barrel chamber to possibly be way too much. Cases should be sized for the chamber they'll be used in for safety, long life and accuracy.

Well, if the chamber and gauge meets SAMMI specs, and the vast majority of the time with the gauges and quality firearms they do, you'll be fine. It certainly beats just screwing the die down to hit the shell holder and sizing cases. And for autos, I think using a gauge is a good way to do it. But yes, sizing to fit your chamber is always good.

 

[Walkalong]

This, or something similar should be a "How much am I moving shoulder/effect on case life" sticky!

Does this thread qualify?

 

[Bart B.]

That shiny ring pointed out in "this thread" always happens when that's the rear most part of the case body that expands against the chamber wall. It does not mean incipient case head separation is starting. When it does start, it's usually a few thousandths inch back of that very normal pressure ring which happens on every new case when it's first fired. The case body forward from it gets polished bright from rubbing against the die body section. Nothing behind it to the extractor groove ever touches anything so that part's usually dull colored.

Picture shows that pressure ring on the case on the right. It's a once fired case flipped over with the thin wall on one side. That ring is all the way around at the same height on uniform walled cases. On that case, its walls are not uniform in thickness.

 

[Walkalong]

Two different things. One is from the stretching/thinning of the case all, the other you mention is just where the case expanded to fill the chamber and leaves a ring that can be mistaken for stretching/thinning of the case wall.

Here is a case that shows the expansion to fill the chamber. There is no thinning going on. And you're right, if it is only on one side the case walls are not very even.