with a 293 grain hardcast lead. My 4 5/8 blackhawk gets 1275 f.p.s. Using 19 grains H110 and a cci 350 primer. These bullets are not gas checked and have a crimping grove to allow a longer cartidge length.
I found the load in a manual which listed it as max for a 290-300 grain bullet in the 41 rem mag.
I have shot 200 of these through my pistol.
I also load 21 grains of h110 and cci 350 primers under 265 WLNGC bullets but have not chronographed these.

WOW!! Where did you get such heavy bullets for your .41. The biggest I have tried are 220gr. LSWC (Kieth Style). I doubt that I will try to duplicate such ballistics out of my handgun but, I would like to get my hands on some of those heavyweights. Please let me know.

The 265 grain bullets I have are Performance Cast Bullets made in Oregon.
The 293 grain bullets are Ace bullet company from here in Alaska.
I found two web sites for heavy 41 cast bullets. One is cast performance bullet company in wyoming that has up to 265 grain bullets. They are the ones who make the bullets for federals premium handgun hunting ammo.
Next is beartooth bullets which has up to 300 grain bullets in the 41.