From Ackley"s handbook:
bullet gains/ powder vel.
235gr 82 4064 2950
86 4064 3060
270gr 80 4064 2800
81 4064 2830
300gr 78 4064 2630
85 4350 2650
88 4350 2740
350gr 88 4831 2650
Not much, but something to work with. Since you're using lead free solid bullets that didn't exist in his day, as always proceed with caution.
Kind of an interesting caliber of rifle. Care to share the story?
Id been looking into a bigger gun larger than my 338 win for hunting bear country after going to wyoming last year. i thought about building a 416 remington, looked at the all the rums. I found out a guy i knew had this rifle for sale its a 375 ack improved built on an interarms mark X action with a douglas barrel crowned with a KDF muzzle break, its bedded, timmey trigger, topped with a 3x9x40 leupold. It came with both sets of dies brass, and bullets. So it was kind of a no brainier for the price i paid.
I played around with a little yesterday with some H 414 powder. I started out with 84 grains and worked up to 85.5 in half grain increments with no signs of pressure. I plan on going up another half a grain. 84 grains shot the best about a 1 inch 4 shot group with 2 of those shots in the same hole, so ill probably end up going with that. All loading was done with barnes 235 grain tsx's.