Resurrecting this because why make a new thread, if a 4 year old one will do?
First off, a note that the last time I fired my CZ-52, I did indeed experience a case neck separation, and had to use a 7.62x39 broken shell remover to get the neck out of the chamber. I didn't have it on me, so that ended my shooting of the Czech Canceler for that day. Didn't buy the Wolff spring, but I did buy a new surplus recoil spring from Apex Gun Parts, which was noticeably stronger/longer than the old spring it replaced. Haven't had it to the range since replacing it, however.
Now on to the purpose of this exercise in thread necromancy... I decided to give forming 7.62x25 from .223 brass a try just for shits and giggles, and as an exercise in self sufficiency. I have plenty of commercial 7.62x25 brass although most of it is loaded up with XTPs at the moment. It probably makes more sense to just buy Starline, though it doesn't appear to be available at the moment. A google search will actually yield a fair number of websites describing how to do this. My 4th edition Sierra manual even talks about it, since it was published in 1995, before the flood of cheap surplus tok ammo hit the market.
I picked up some apparently once fired commercial .223 brass at the range last year, and finally tumbled it up last night and tried my hand at case forming. Many of these had badly dented and crushed neck/shoulders from being stepped on, but I didn't care about that since the first step in forming is to cut them off to 1" length. Most of the sites I searched recommend using a roller tubing cutter, which seemed to work okay, although they leave a bit of a burr, which will be erased by subsequent steps anyway. Mostly it's just slow. Here's a picture of a case in the tubing cutter, along with the soft jaw pliers I used to grab the brass without gouging it up:
The Lee resizing die had no trouble forming the brass... As some of you may recall, I use a Forster Co-Ax press, and it barely took any force at all. Some of the sites showing how to do this mention removing the entire decap assembly, but if there is a reason to do this with the Lee dies, I can't see it since they don't have an expander on the sizing die, despite being a bottleneck cartridge. Here's a formed case, with some rough cut ones ready for forming:
All of the sites talking about doing this mention the need for reducing case wall thickness at the neck, usually using an inside neck reamer. I bought such a reamer in .308" for my Forster case trimmer, only to discover that it is actually about a .311" reamer. It's made for some other loading operation wherein the necks are reamed prior to sizing, though for the life of me I can't understand why anybody would need to do that.
Using a combination of micrometer, small hole gauges, calipers, and some commercial brass, I determined that the reamer I actually need should be about .302" (letter N) to make the neck wall thickness the same as the commercial brass. Trimmed to the same length as the commercial brass, and after expanding, I should be able to use the same crimp die adjustment, and not have to worry about feeding problems due to neck thickness. Custom reamer is on order from Forster (at a cost which would have bought about 200 pieces of Starline brass, hmm
).
A couple other things I discovered... My Forster case trimmer is too long to trim 7.62x25 to length... I have to order a shorter base. That and the new reamer should allow me to ream and trim in one step. They make an adapter for a power screwdriver which I am probably going to buy, and which would have saved me a lot of time trimming .308 cases a while back. I like that idea a lot better than the drill press setup that Forster sells.
Also, there is
this site which shows all the steps in forming Tok from .223. He uses an outside neck reamer to accomplish the same thing as I am doing with the inside reamer. He's also got a link to a
miniature chop saw from Harbor Fright, which may be just the thing for doing a cleaner, faster job of trimming the cases to length prior to forming. You could rig a depth stop, and cut them pretty fast. I think I'm going to get one, because it would be useful for a lot of other things as well.
Who knows, with the power tools it may be possible to convert the cases over fast enough for it to actually make some small amount of sense.
