I use the COW method, although I prefer coarse cornmeal, or grits for filler. For powder I use Unigue and vary the charge by case capacity. to form 240 Gibbs and 6.5 280AI I use 14 grains. I fill the case to the top with filler, and finger press a dental wax plug (.035"0 cutting it in Place with the mouth of the case. For cases that require a very large bore increase, my Gunsmith builds a fireforming chamber from drill steel using the chambering reamer, and turns the OD into a 12 Guage shotgun case that drops into a 3" chamber. I do my .411-284 wildcat this way with the COW method and blow out the neck to full diameter in one shot with no barrel wear at all. I form my Gibbs using 270 win cases necked down to fit the chamber, and trim after fireforming.I have a 25-06AI build in the works that I will hopefully have finished by deer season. I'm in the process of gathering up all the reloading components and I got to thinking....why would I waste the "good" primers and powder heck even cheap bullets ain't cheap anymore on fire forming?
My chamber will be set up properly where I can shoot factory 25-06 ammo out of it. But I hear that makes short cases that aint gonna grow much especially in an AI. And factory ammo ain't cheap or easy to find. Also this is going to be a 1:7.5tw so I don't know how well a 100gr sst or corelok would hold together to hunt with while fire forming. Also not planning on using Remington or hornady brass. I have 150pcs of lapua 30-06 so far.
I've used the c.o.w. method before but in a 223ai and that was when primer bricks were $35 and that is a much smaller case.
Barrel life is of concern. But I'd rather do something right the first time so if that means fire forming with a bullet then so be it.
Can I load a medium charge of superformance which a have a lot of and a cheapo bullet and a cheapo primer and start there? Would using a cheap primer for fire forming change my primer pockets?
This isn't a 25-06AI specific question. How do yall fire form your improved cases?