M1A split case heads

[Shooter88]

If they're being FL resized, yeah, I'd toss the 30-06 after 4 or 5 as well.

Yeah, I have always FL resized all of my brass. Thankfully I have not yet had any case head seperations with those.

Buy some new brass, ya cheap so & so!

Haha, looks like I'm gonna have to.

[Innovative]

Check out the Digital Headspace Gauge ...

You should NEVER get a case head separation. It doesn't matter how many times your cases have been reloaded. You can avoid this symptom if you measure the clearance (at the shoulder) that YOUR handloads have in YOUR particular chamber. Then you can set your FL die height perfectly. Look into the Digital Headspace Gauge.

[Shooter88]

You should NEVER get a case head separation. It doesn't matter how many times your cases have been reloaded. You can avoid this symptom if you measure the clearance (at the shoulder) that YOUR handloads have in YOUR particular chamber. Then you can set your FL die height perfectly. Look into the Digital Headspace Gauge.

Sorry for sounding like a newb, but how exactly would I measure this? I bought a case gauge today online. Not a digital one though.

[five.five-six]

every time I load .308, I put a hash-mark on it with a sharpie and darken the existing hash-mark(s)

[Shooter88]

every time I load .308, I put a hash-mark on it with a sharpie and darken the existing hash-mark(s)

Thats actually the exact way I planned on keeping track of mine.

[five.five-six]

sharpie holds up surprisingly well through firing, tumbling and sizeing

[30Cal]

You should NEVER get a case head separation. It doesn't matter how many times your cases have been reloaded. You can avoid this symptom if you measure the clearance (at the shoulder) that YOUR handloads have in YOUR particular chamber. Then you can set your FL die height perfectly. Look into the Digital Headspace Gauge.

For functioning and slamfire prevention purposes, you should set the shoulder back every time for a gasgun. And when you fire, it's going to stretch. Each time, the head is thinning and getting work hardened. Eventually, it'll be hard enough and thin enough that it'll crack instead of stretch (assuming the necks don't split out first).

I would agree that you should never get a separation (but this depends on conservatively setting a limit on how many times you fire your brass) and that if you are sizing excessively (creating a long headspace condition), then they're going to come apart a lot sooner than they should. I'm a firm believer that if you're pushing the shoulder back, you ought to know how far, and to do that, you need to be able to measure.

[Innovative]

There's now a better way ...

30cal .......

Slam fires are not caused by the ammo unless your primers are seated too high. Handloads for a gas gun should have -.002" to -.003" clearance at the shoulder. A bolt gun can do even better with -.001" to -.002" clearance.

My website shows the Digital Headspace Gauge, and the instructions explain how it's used for a bolt gun. This is a much more accurate method of resizing. Smoked cases, magic markers, scotch tape and paperclips are no longer the best way to go.

[17+1]

I would reevaluate how far your pushing the shoulder back on your reloaded rounds vs. what the dimensions in your chamber are. I hear a lot about people who reload their cases 6+ times usually end up getting split necks not case separations.

1 . Either your head space is off on your rifle and bolt combo and your in spec ammo is getting stretched after being fired in a sloppy large chamber.

2. Your rifles chamber and bolt are fine but your re-sizing the brass and your pushing the shoulder too far down. This may be causing a head-spacing issue when you load the brass into the rifle. When you fire the round it tends to want to stretch to take up the 'slack' behind the end of the cartridge and against the bolt. You may not be re-sizing the shoulder past the spec too much, but over 10x firings the problem has a chance to get to the point it breaks.


In my opinion, I would check the rifles head space. If it is deemed good to go by a gunsmith then I would use a case length gauge and drop some reloaded rounds into it. They normally have steps that will tell you if you didn't size your round enough or if you OVER re-sized the brass too much. If the ammo checks out OK through the gauge then I would just continue the paper clip tests after 4 firings. Keep testing them after each firing and once you notice any dip I would chuck them.

I bet the head space is fine. M14's are just really hard on brass. I get 3-5 firing depending on which brass I'm using. The head space in mine has been checked by a gunsmith.

M1A's and M-14's (with a 7.62 NATO chamber) are very hard on brass and it is recommended that after four or so firings, the brass gets retired. You've reloaded your brass way too many times.

Read Zediker's downloads on reloading for the match M-14 and the Once Fired Twice Fired articles. http://www.zediker.com/downloads/m14.html

I've been shooting and reloading for my M1-A since the mid 70's.

If you want to set your dies to set back the shoulder a few thousandths for your chamber, turn the gas spindle to "OFF" and fire 5-6 cartridges and cycle the action manually, then do your measurements. The M1A and M-14 blows the shoulder a little farther forward during the extraction/ejection process. If you measure from normally ejected cases, you will get false readings.

I've always been paranoid when resizing for my M1 and M14. I set the shoulder back all the way with FL sizing dies. I am using once fired M118 from the 60's, 70's and 80's as well as current production Winchester NATO brass. I get spliting on the fourth firing with the cannelured M118. The non-cannelure M118 and Winchester will typically start to go on the 5th or 6th firing.

From my experience, the Frankford Arsenal match brass seems slightly more durable than the Lake City match...

[Innovative]

There is a better way ...

17+1 .........

Your cases are splitting because they are repeatedly stretching too far at the shoulder. That can be avoided by setting the shoulder back accurately, and that requires "measuring" to set the die height.

When the shoulder is pushed back too far, the case stretches too much every time it is fired. That excessive stretching soon makes brass paper thin, just above the web.

Your handloads should NEVER get a case head separation, and your case life should be 3 times what you're getting.

[Pete1979]

I bet the head space is fine. M14's are just really hard on brass. I get 3-5 firing depending on which brass I'm using. The head space in mine has been checked by a gunsmith.



I've always been paranoid when resizing for my M1 and M14. I set the shoulder back all the way with FL sizing dies. I am using once fired M118 from the 60's, 70's and 80's as well as current production Winchester NATO brass. I get spliting on the fourth firing with the cannelured M118. The non-cannelure M118 and Winchester will typically start to go on the 5th or 6th firing.

From my experience, the Frankford Arsenal match brass seems slightly more durable than the Lake City match...

+1, I use small base dies for the M1 and the M1a and check them with a drop in gauge.

It is NOT likely a headspace issue.
If I take a new 308 case that measures say 2.005 and shoot it through my R700, after sizing it may measure 2.008. The same case fired from my M1a will measure 2.014. I tried this with some new primed FC 09 cases that I got from Brassman last year and was amazed at the difference since my M1a is near new and has a tighter chamber than the 700, 1.631 (on the tag that came with the gun vs 1.632 + change measured with the RCBS precision mic, 10 case average.
I have a box of LC 69 brass and a bag of LC 68 match brass that I use in my M1, both were unfired pull down. I usually ****can the cases after load #3.
I Use once fired LC for the M1a which is also a NM, use them 2 or 3 times then leave em where they fall.
The Garand style action yanks the hot case out of the chamber before it has a chance to contract, Zediker says its just the nature of the beast...

[NRAhighpowershooter]

I get 8 loadings out of my LC91 brass in my match M1A and that is only because I lose the primer pockets at about the 8th firing...

[Innovative]

NRAhighpowershooter .....

Have you ever tried Federal or Winchester cases? I don't have primer pocket problems with them.

[NRAhighpowershooter]

NRAhighpowershooter .....

Have you ever tried Federal or Winchester cases? I don't have primer pocket problems with them.

I have found that federals last me only 4 -5 firings before the primer pockets go.. I haven't tried Winchester.. I only use LC or TW GI brass for my HighPower matches and such...

[Innovative]

Pete1979 ......

In most (but not all) cases, SB dies are seldom required. The amount of contraction of fired cases (after cooling down) is in the range of ten thousandths - not thousandths.

You can verify the exact size of your chamber by disabling your gas system, firing a round, then comparing it (at the shoulder) to one of your regular fired cases.