A couple of years ago, I came by a .50 calibre mould that throws 540 gr bullets. I sized them to .512 like I do my Lyman 515141s and tried them in my Shiloh Military Rifle (1 x 36" twist) over 65 grs FFg. One out of three tumbled at 50 yards and recoil got my attention .....
When my new 50-70 Shiloh carbine arrived, those rounds would not chamber as I had neck sized them only. So, I modified a Kinetics 'hammer' type bullet puller to yank the lead, salvage the powder and full length resized the brass.
I just reloaded them and they chamber just fine in the fast twist (1 x 26") carbine, which has a left hand twist, BTW. All my other Shilohs have a right hand twist. I expect these loads to be 'thumpers' at both ends.
While I was at it, I loaded up some 365 gr bullets over a full 70 grs of FFg. From a Rapine mould, they are nominally a 375 gr and miked .520. They swadged down just fine in my .512 die.
First time I ever got that much powder under a bullet in a 50-70 case. I'm hoping it will serve as an 'Express' loading for deer and black bear. It will be interesting to see what rate of twist handles this lightweight bullet best.