Fire forming cases

[Caster]

Typically I fire form cases with a cheap FMJ and a starting charge of whatever.

I have one lot of brass dedicated to a specific rifle. The rifle has a slightly oversize chamber, and I want to fire form them before I start loading them. I know there are several methods. I have nearly a pound of bullseye I will never use for anything serious, SO, I wonder if anyone has an idea of where to start? I thought about turning some wooden plugs and loading the cases with a charge of bullseye and some dacron filler. What would be a sufficient charge to expand the brass?

BTW, it's in a 7,62x51 Ishapore I am setting up for a "Cast boolit only"​ rifle.

[Okey]

I form my Dasher brass with pistol powder using a false shoulder. Have used Clays and #2 powder. The 6br filled up into the shoulder form the brass about 95%. Have also filled a .223 case up to the top of the shoulder without any pressure signs. Would start with a little less powder.

I stick a little toilet tissue in the end to keep the powder from falling out. Below are 2 formed cases and several more ready fire. Warning... It is loud I use double ear protection.

Okey

[Caster]

Thanks!

[dlm37015]

i use red dot then fill the case with cornmeal shoot up in the air

[Caster]

Okey, could you elaborate on the "false shoulder" and how it can be done with a .308 please?

[mikegideon]

Okey, could you elaborate on the "false shoulder" and how it can be done with a .308 please?

Looks to me like he's forming 6mm Dasher cases out of 6mm BR cases.

[Okey]

This will explain it better than I can. It is also the place I learned.

Forming 6BR Improved Cases

Okey

[Caster]

Okey, thanks bud, I appreciate it. That makes PERFECT sense once you actually see what's going on. Thank you, now I have to turn me a new expander ball and get started.

After reading that, I can look at your picture again and actually see what's going on. It's always cool to learn something new.

[Okey]

You're welcome. I tried them the jammed bullet and false shoulder method. The cases with false shoulders retained the original length, formed as well if not better and didn't waste bullets. The ones with jammed bullets shortened about .010.

Okey

[LngRngShtr]

When making new brass I just get them close and load "bunny fart" loads for the caliber it is going to be if I am only making a small batch like a .401 Herters or such (think .41 Special) ..once and your set for ever it seems..

I would probably go with the cornmeal or fluff method if it were more such as a rifle...as I can see that getting expensive but if you cast your own maybe not so much..

I have accidentally fire formed some .308s in my Garand once so the fire forming process is pretty forgiving.. I was young and we had 2 Garands that day unbeknownst to me one was a .308 conversion... it shot and cycled fine just hit a tad low at the 200 yard mark...made an old Gunny laugh and say he had done that many years before at a match,.. love them old shooters stories..