Reforming 223 to 17 Mach IV

[MrMagumba]

I'm looking for an economical way to feed my 17 Mach IV, but 221 Fireball brass is pretty expensive. I could get reforming dies for 223 to 221 for about $100, and get 223 brass for about $.25 each. After a few hundred rounds I figure I would have paid for the dies. So what kind of problems might I run into reforming 223 to 221 then using my existing reforming dies which take 221 down to 17 Mach IV. I already turn the necks on the finished product. Would I also have to ream the necks? It seems straightforward, but maybe there is more to it than I think.

 

[LoonWulf]

only thing i could think of is reduced capacity if internal taper is different. What happens if you lop off the top of a .223, then run it thru a standard 221, die then your M4? dunno if it would help but ive got a 222 die set you can have, that will push the shoulder back some.

....or use 300 aac brass? ive got some of that if youd like to try, thats a hell of a reduction tho.

 

[MrMagumba]

I sort of tried something like that. I tried to run a 223 case in my Mach IV reforming die which takes the neck down to about 20 cal. When it hit the shoulder it wouldn't move any further. The Mach IV form die is basically the 221 body and shoulder so a normal full length sizing die in 221 probably won't move the shoulder down very easily. I suspect the 223 to 221 forming die has a much more gradual way of moving the shoulder down. I thought about possibly ending up with cases of slightly different capacities than I'm used to. That could play havoc with all the load work up I've done so far, since tiny changes have big effects in this little case. I'll have to measure the capacity difference if any and hopefully a couple tenths powder change will get me back to the accuracy I had before. Thanks for the offer on the dies. I think my best chance of success is to start with something specifically advertised for the job.