As this is more relevant to reloading, I thought of starting a new thread here rather than the one I have on the GUNSMITHING FORUM.

I built a 223 Ackley, and was in the process of fireforming cases for it.

I have a load of locally made 223 military military ammo which I have kept the brass from.

So I took just over a 100 of them, and loaded them with bulk Remington 50 grain SP bullets and 24 grains of Reloader 7.

While sizing the fired cases, one broke in half inside the die!!

I have never had this happen before.

I looked at the rest of the cases which I have fire formed, and not all looked the same.

Some had a decidedly marked expansion ring, and others did not.

I can feel the incipient crack very easily with a pin, while other cases formed perfectly without any problems.

I will take photos and post them.

You can clearly see the difference in the two cases.

They are from the same lot once fired military ammo.

Goes back to the old saying measure twice cut once.

these look just like a problem i had with a 6x45 only mine split on firing - ended up being old brass - forming from new brass fixed the problem - one other thing with military brass is that if it came from machine guns - they often have rather loose hambers

what gain did you get from the IMP? roger

Had need of a broken case extractor for 5.56 just once. Was shooting tracer reloads after alot of steel. Was far from home base. Happily, someone had a .35 cal bronze brush and we jammed it in, then tapped from muzzle. Easy.

Inspected the remaining ammo and sure enough could see occasional incipient separation exactly like Saeed's pic.

Some opine it's best not to purchase/use bulk 7.62x51 or 5.56 once-fired brass. I'm OK with it, but always headspace die check and/or do a quick inside feel with a wire pick.

Out of 106 cases I have fireformed, one broke in half as you can see in the die, 8 show signs of splitting from looking at the from the outside.

The rest seem to be just fine.

I ran a bent wire inside some of these, no problems of an incipient break.

All cases had crimped in primers, but some do accept the primers as normal, some are very tight.

The tight ones I am going to run through a primer pocket swager.

Then I will load them and shoot, and see how things work out.

Out of the 106, and further examination with a bent wire, I ended up with 72 good cases.

34 were showing signs of cracking.

I will shoot the good ones, and see how long they last.

And amazingly, after 106 shots, there was no copper fouling at all???

Velocity was average 2825 fps.

What kind of rifle were they "once fired" in? Semi auto?

I presume that the tolerances in semi auto actions are not as tight as bolt actions.

I have no idea but they do not look that they were fired in semi autos, as that normally shows some dents.

Got a great group yesterday.

25.4 grains of Reloader 7 and 52 grains Brawand, RWS 4033 primers, 3510 fps and a 5 shot group of 0.195”.

they are all stretched like that.
you can just see it on some and some went far enough to pull apart.

you made the case body longer and larger in diameter at the front.
the metal has to come from somewhere.

I bought some .300 AAC brass made from once fired .223 cases. While resizing before the first loading, I had a case separation inside the resizing die.

I may be completely off base, but it made me wonder if the brass wasn't a mix of rounds fired from semi-auto and a SAW (full auto). Imagine brass from the full automatic experiences a different set of stresses depending on how the round is situated in the chamber (and the tolerances of the chamber) when it is fired.

I was talking to a friend here who has a number of Improved cartridges, and he says he has had this happen many times!!

He gets all his cases from shooting ranges.

Well, I have developed many wildcats, on improved cases, and have never had this sort of thing happen before.

I have always used new brass from a known manufacturer.

Back to this one.

Here are some results so far.

You already see the results of the 52 Brawand bullet above.

Next I tried the Berger 45 HP.

Same cases, same primer.

25.0 Reloader 7 3554 fps 0.429
25.7 3717 fps 0.557
26.4 3868 fps 1.287

24.0 VVN 130 3292 fps 0.258
25.0 3493 fps 0.348
26.0 3657 fps 0.508
27.0 3806 fps 1.356

I will try the Berger 30 grains next.

For awhile I had case separations with .223 cases necked up to make 6x45mm. I kept a 1/4-20 tap with the handloads for getting cases out of the chamber.

Tried the 30 grain Berger and VVN 130 powder.

25.0 3801 fps 1.040"
26.0 3948 fps 0.839
27.0 4167 fps 0.709
28.0 4360 fps 0.893

MIlsurp and used brass, much of which has been fired in automatic firearms and they have over size chambers as a rule or at least the military autos seem to and brass is maxed out..resize and anneal is the answer but is it worth it, not to me..I just buy new brass to start with, mostly for my 6x45 from 223 brass..

Too much range pick up brass out there today, some has been "reconditioned" or simi reconditioned whatever that means, but doesn't sound good to me!!

Same with .308 but not so much..