Fire forming question

[jrdragdad]

I am building a 6mm-06 improved and will need to fire form brass. Has anyone ever tried using IMR Trail-Boss powder as reduced loads to save barrel life yet still break in the barrel and fire form the brass?
A max load in a 2506 of 19.2 grains with a 100 grain bullet will is said to be appx. 1700 fps @30600psi.
IMR also has formulas for other cartridges.
I know people who are using it for subsonic ammo just wondering how it would work for this application
any thoughts?
thanks

 

[spclark]

I think your aporoach is valid in that you've picked a cartridge that's very close to the one you'll be working with. Were I doing similar I'd knock a grain or more off the 25-06 starting load to start.

F'forming with reduced loads may not properly form brass unless & until it's been fired several times, which kinds of offsets the savings in powder and barrel life sought by using reduced loads. One f'forming however will get you closer of course, and as I've lately become an advocate of using somewhat reduced loads in virgin brass (may help work-harden case heads & avoid premature primer pocket expansion with full-power loads later on) it's not a bad idea.

Folks also f'form using pistol powder in bottleneck rifle cartridges but with no bullet. The idea is the faster powder gives very quick pressure that forms the case walls. Sometimes an inert filler like Cream'o'Wheat cereal is used on top of the powder charge, maybe even a Kleenex plug on top of that as a case sealer.

This saves barrel wear of course at the expense of time and powder burned but does do a better job faster than using low-loaded break-in loads using bullets.

 

[284driver]

Reduced loads wont blow the shoulder out. I fireform virgin 22-250 brass with near Max 22-250 load in an ackley chamber and it is flat out accurate.

 

[jrdragdad]

Thanks for the replies. I never thought about work hardening the case heads but it does make sense.
Thanks