Headspace issue w/ 5.56

[erikor]

I acquired about 800 pieces of fired 5.56 brass, all of it LC91 and LC92. It had been fired, deprimed and sized. I ran it through my LE Wilson cartridge case gauge and found that about 1/4 of of the cases have had the shoulder set back too far (the case guage swallows the base of the cartridge while the cartridge mouth sticks out beyond the end of the gauge. The amount varies from "just barely" to maybe one case wall thickness. OAL is good.

Can this brass be salvaged? Resizing won't bring the shoulder back to it's right place, and I can't fire-form it. I bought the brass about a year ago for a VERY reasonable price, even at that time, so I won't feel bad about scrapping 200 pieces. The brass is otherwise in very good shape, I think the previous owner just had his sizing die set too deep for these cases.

Erik in Oregon

Information

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[MEHavey]

Were it mine, I'd consider that one firing is most likely not going to do anything bad, especially with military brass and it's relatively heavy case wall thickness to put up with the resulting case stretch -- once. Thereafter proceed as normal.

Three things to consider:

- Are you reasonably certain it's once fired?

- Have you borrowed/bought an RCBS Precision Mic and compared its readings? (For some reason, the Wilson gauge readings give me fits. The RCBS tool gives me data. Hornady's tool is even a tad better/faster, but `ya gotta have a digital caliper to use it.)
RCBS Precision Mic - Headspacing and optimal Bullet Seating Depth
Sinclair Headspace Tool Set

- The opinions of the rest of the peanut gallery here who will weigh in with their own experience.

[jjroth]

didn't have the sizer correct and pushed the shoulder and neck back, almost folded over itself.

fireformed using 110gr .30Carbine and lowest powder load ffrom Sierra's manual.

lasted about three more then scrapped.

Attempt two, and see what resuslts are, maybe use a bolt action to located under rxtractor then fire..

If works then segregate cases and use for practice.

[MEHavey]

To give you some data for judgment/comparison, take a look at this chart…

http://www.ar15barrels.com/data/headspace.pdf

…and compare the differences between the civilian "NO-GO" measurement, and that of the Colt Field-II measurement. It's almost 0.007" ( ~ 1-1/2 aluminum coke can thicknesses.)

Note also the SAW Field measurement is 0.035" out from the Civilian NO-GO (35 thousandths ( 7 coke cans ! ) That's really "stretching it" (pun intended), but it shows you how the military headspaces their machine guns to make sure there are no partial bolt closures, and how much they think a headspace can be long w/o fear of head separation (putting the gun totally out of action) on first firing. (Again note that SAWs get really hot under sustained firing and chamber dimensions tend to close up a bit. But even a cold SAW fires with this kind of headspace gap w/o significant risk of stoppage.)

-- It's also why you want to watch out for pick-up machine gun brass.

Food for thought only. Don't depend on this kind of slack unless you're in a firefight.

[Litt'le Lee]

then see if they will chamber and extract--if so I say shoot um--they will fire form