Fireforming brass.

[ShadeTree]

P.S. It's been a while but in thinking about it, I believe on that 22-250 I also put a minute amount of sizing oil on the case body before fireforming. I wont do that with this rifle because it's not that far out. But I theorized that by not allowing the case to grab the chamber, the stretching would be dispersed across a greater area rather than starting at one spot.

Greased up the back of the locking lugs also. Can't say for sure if I did it all the right way or not, but it worked out good.

 

[358 WCF]

Good info 358. I've done the false shoulder out of necessity to minimize case stretch on initial firing of new cases on 2 different rifles that worked out nicely, but that was with standard dies.

I'm not following exactly why the AI die would cause an issue necking down the expanded case mouth to the right depth for the new shoulder since the parent case shoulder is shorter than the AI and the die should stay off of that, but I'll take your word for it and keep an eye on what's happening.

I might follow your advice and try a couple both ways and see how it's working out. False shoulder, and bullet jammed. Or might just try a couple with a false shoulder and if it's working well, stick with that.

The body/shoulder junction in the Ackley die doesn't support the standard case in that area. I have to move the shoulder forward about .030" in my sloppy old 22-250 Imp. & have collapsed more than one case in the Ackley die when necked up to 6mm & sizing back down. It takes a few years to wear out the brass, so I have brain farts on the 1st case sometimes. Maybe it's the thin WW brass I still have bags of? Will try some Lapua if it ever comes back in stock before the barrel gives up the ghost. Never a problem in the standard 22-250 die. As always, YMMV. Just a possible scenario that ruins perfectly good brass.

 

[RL338]

Winchester brass necks and shoulders are soft out of the bag. I learned you have to fire them once out of a standard chamber to work harden them first. Then you can set your false shoulder.

 

[358 WCF]

Winchester brass necks and shoulders are soft out of the bag. I learned you have to fire them once out of a standard chamber to work harden them first. Then you can set your false shoulder.

Could be, but not a good option with all that headspace & no standard 22-250 anymore. No problems with using that soft WW brass in standard dies for the first load. Looks like 2 ways (at least) to skin that cat. The 1st batch of brass may have been RP but it was long ago & I'm too lazy to dig for the records. Just passing along my experience in case it happens to someone else.

 

[Ridge_Runner]

properly chambered AI rifles headspace .004 shorter than the parent cartridge, so you can shoot factory ammo through them.