I loaded a 335 grain cast lead bullet over an almost compressed charge of H4895 in 375 win. It is doing about 1600 fps in a 21 inch barrel. According to Hodgdon, you can reduce charges of H4895 to 60% of the max load. I bet I could get it subsonic.

The 375 project has been put on the back burner for now. Working on a couple of new projects.. A 357 mag., 158 cast, with 6 gr. trail boss. Consistantly in the 1080's. Shoots real nice so far. Waiting on some 215 gr., but I probably won't have enough case for trail boss...A 454 casull with 300 gr. Hor. in reverse and 11 gr. of trailboss...And darn what a hole. Under 2" at 100 with a red dot. (All of the above is safe in my guns.) Will be going back to the 375 shortly. Always looking for a reason to shoot more. I appreciate the info. Will give it a try.