Reloading machine gun .308 brass

[swift]

Thanks, everyone! I learned a few tips today.

[ar15barrels]

Also, don't forget that military rifle brass is typically thicker than commercial brass with less case capacity.
I would start with reduced loads (by a few grains) and see how they work.

Dan

For 308 Winchester loads, it's normal to reduce powder charges by 1 (one) grain to accommodate the reduced case volume of 7.62x51 military brass.
A "few" is too much.

[J-cat]

1.5 grains is more like it. Powder lots vary in burning rate.

Secondly, in 308 brass, military vs commercial is too blurred. Many commercial cases are just as heavy as military. FC and LC are a good example. They have the same capacity. PMC, CBC, Starline, some Hornady, some a Winchester, etc are the same as military. Some military cases are the same as commercial. You can’t just assume. Weigh the cases.

[bigdrunk92037]

I had the same issue.

When I loaded some of that stuff I had about a 50% incipient head separation at the next firing in my gas gun. I will never waste my time again with machine gun brass again.

[fguffey]

I had about a 50% incipient head separation at the next firing in my gas gun

Suddenly and without warning: Reminds me of neck tension; in the world of reloading it is not possible to measure, there is no gage to measure neck tension, with one exception. I have a tension gage, my tension gage does not measure tension it measures bullet hold in pounds. The largest tension gage I have used was face size, it measured tension in thousands of pounds, it was possible to convert thousands to tons but all of that drill pipe was weighed in thousands of pounds.

No one ask how much tension do we have on the bottom of the hole. Read the indicated weight on the pie size gage and then multiply the indicated weight by the number of cables.

Again, I ask; does anyone have a machine gun barrel? Does anyone in the world of reloading measure before and again after firing? Does anyone know/understand the sequence of events necessary to have case head separation? I was told I was going to have case head separation and I wondered; what had to happen before the case suffered case head separation. I knew my cases were not going to have case head separation when I measured the case after firing the first time.

And then I tried to determine if it was possible to suffer case head separation before firing, test indicated I was not going to have case head separation; and then I thought, if I can do the test anyone can do the test, after that I rationalized, if I can why can't they?

F. Guffey

[M1NM]

Also, don't forget that military rifle brass is typically thicker than commercial brass with less case capacity. I would start with reduced loads (by a few grains) and see how they work.

Dan

It's not so much that it its thicker it's harder. The old M1 30-06 brass and 7.62x51 brass is much harder to take the hammering it suffers when cycled. Normal 30-06 and 308 brass will have the rim torn up/off after a few reloads for an M1 or M14.

[fguffey]

I have a bag of once-fired .308 lake city brass that took noticeably more effort to full-size resize than my two-times fired

More effort to full length size: Why were you trying to full length size? You had cases that you had fired and sized twice, it seems you would know the length of the chamber from the datum to the case head.

The case length was 2.020”, a normal case length for the 308W is 2.015”, and then it should be decided when the measurement was taken; before or after sizing. When determining the effort required to full length size the reloader should consider the difficulty in sizing the case head above the shell holder (deck height of .125”)

In these matters I never remember reading about checking to see if the die made it to the top of the shell holder. I know, reloaders are so full of tension, moving the shoulder back, bumping and head space of the case; I guess ‘too busy’ could be a good excuse.

But it is possible if the cases had more resistance to sizing than your other cases I would think it would be wise to determine if the die made it to the shell holder. The case’s ability to resist sizing can prevent the case from being sized. Tuff t size cases can cause the press to flex. Press flex can be measured but never on the Internet. I have measured press flex; I have a tension gage that measures flex. Problem, the gage is not marked off in tensions; it is marked off in thousands and pounds like a strain gage. When it come to knowing if my press has more ability to size a case than the case has to resist sizing I measure the gap between the die and shell holder. And then there are methods and techniques for increasing the presses ability to size the case.

And then there are all of the reloaders that have case head separation, if I have case head separation I want to know why. I have never blamed case head separation on the case; I have blamed reloaders for what they did to the case.

F. Guffey

[mskochinski]

I use these machine gun fired cases often for my M1a and AR10. Cheap and these two guns are gonna beat the crap out of the cases as well, so why not, the LC are tough and up for the job. As mentioned always check for separation, paper-clips work just fine, and for me after the initial resizing is done and trimmed to length, I love using my X-Dies to keep the growth of them in check. For me works really well, I usually do 4ish reloads on the case then toss them. Not worth any more risk, some can get more, the bolt actions definitely, but on these two semi-auto's they are harsh on them and not worth it.

https://www.rcbs.com/reloading-dies/rifle/356090.html

[ptmn]

I use machine gun fired brass. I had to use the same technique Jcat mentioned about sizing first in a standard die, then in a small base die.

I tried just the small base die, but the amount of pressure on my press handle was getting stupid and it was putting a ring on the outside of the case near the bottom. I went to the two step method of a regular die, then the small base die and that made life much easier and I didn't get a bunch of cases with a ring at the bottom.

Can't say how many times the sized machine gun fired cases last, since I only used them in my HK-91. That gun has a fluted chamber and it crushes the entire case mouth on ejection, so I only use the brass once. Which is the reason I use cheap machine gun fired brass.

[swift]

Was using small base die

Good point on the sizing die-I was using a small base 308 die and sizing in one step. Using a standard 308 sizing die first makes a lot of sense.

[roostersgt]

I've done thousands of military 308 and have noticed that you have to really lube them well before sizing. Have not yet had any issues with pressures ,or case head separation. Load mil brass about half grain less than commercial. Only issue I had with mil brass was they all had to be trimmed and the primer pockets deburred of the crimp. A real time consuming pain in the ***. Have several hundred ready for loading and several thousand already loaded. I'll probably never buy them again because of all of the extra work involved.

[MG34]

I use nothing but Lake City brass for my M1A. I use 41 grains of IMR 4895 with a 150 grain Hornady FMJ bullett. I also use a RCBS Precison Mic Gauge to make sure I don't over size the case.

[freonr22]

I think you need 10 neck tensions, for machine gun barreled brass, i could be wrong

[ar15barrels]

I think you need 10 neck tensions, for machine gun barreled brass, i could be wrong

Now you did it.

[freonr22]

Well, that, and maybe bumping the shoulder back 300