I have done it many times. I have a Marlin .375 and while I have a few hundred .375 Win cases and about 10 boxes of factory ammo, I reserve those cases for jacketed bullets. I like the 38-55 cases for cast bullets because they are slightly thinner and it is easy to fit a cast bullet that is slightly larger in diameter. My Marlin likes cast bullets that are .379 but shoots jacketed bullets that are .375 just fine. The 220 grain Hornady is a great deer bullet if you can find some. The company you are referring to must be Buffalo Bore and I agree with their info.
I used the formula that Ross Seyfreid use to write about to come up with a cast bullet load. He wrote that you can use 40% of the black powder weight of 4198 (either one). 40% of 55 is 22, and while that works, experimentation revealed that 20 grains is more accurate in my rifle. I have also stopped using the filler he wrote about because I could see no difference in accuracy. I mostly shoot the Lasercast 240 grain cast bullets in those loads and they have managed some one inch groups at 75 yards, with my elbows on the bench but the gun in my hands. I think that gives me a better approximation of what I can do from improvised rests in the field than putting the gun on sand bags.
Just wanted to add that 8 grains of Red Dot with the 240 grain cast bullet is an accurate small game and plinking load that is fun to shoot.
Last edited by doubletap; 11/14/18.
