Cast Bullet Powders?

[.22-10-45]

Hello, I am working with a .450/.400 3 1/4" Nitro Express in a 1901 Fraquharson single shot rifle. Using 300gr plain base Ideal 412263 for starters. Someone suggested IMR 3031 as a viable powder. I have used Varget , H4895, and A5744 in a .40-70 2 1/2" Sharps Straight with above bullet with good results..would these be usable in this BIG case? I am starting out with test loads of SR 4759..but would like something to fill that case better. I talked to the Tech. at IMR and he suggested TrailBoss..35.5gr. fills case to bullet base..for max. load & starting load is 70% of that..what are your opinions? Thanks alot!

[Larry Gibson]

Those powders should work well in the larger case. I suggest a dacron filler (just enough with the dacron "fluffed" to fill the air space) with all of them and I would start with the 4759 as you are, then 5744, then H4895 and then the Varget. with the slower burning powders you may find the velocity is too high for best accuracy from the PB'd bullet by the time the powder burns efficiently, even with the dacron filler. Let us know what you find.

Larry Gibson