I don't have that gun, but my Thompson Seneca in .45 is listed at 90 grains max with PRB and 80 grains max with conical. Some are rated a little higher, but I haven't seen a lower max load in a .45 rifle, so that might make a good limit till you know for sure. 70 grains is usually a pretty accurate hunting load in the .45's though, and it's what I use. As you get near the max, accuracy fades fast.