You should get in touch with MacD37 (aka Dugaboy). He made the same suggestion to me when I was thinking about getting/converting the 45/70 Pedersoli. Maybe he could help you find a starting point. I know I had a hard time finding published smokeless loads, although my old Lyman manual has some (not up to the 450 Nitro levels). Mr. Searcy built a 45-120 as one of his doubles on a shotgun action and it was regulated for a fairly stout smokeless load, albeit with 400 grain X-bullets.

I think MacD37 usually spends more time in the Big Bores or African Hunting forums, so if you can't reach him through this post you could email him or try him over at the NitroExpress.Com forums. He has always been helpful in answering my questions about doubles.

Jack Huntington has converted Kodiaks to 45/120/3 1/4" to make the process easier that going to 450 NE. He recommends just loading the old Sharps up to NE velocities, i.e. 500 gr at 2150. Anyone got any particular loads like that they'd recommend? Can you use the British Double Rifle loads for the NE just as easily? Anyone there? Hello?

Sarge,

I looked into this once, and actually checked the case capacity (at least the capacity of the brass that I had on hand). The 450x3.25" NE (A-Square brass) capacity was 133.4 grains of water. The 45-120/3.25" (RCBS basic brass) capacity was 127.5 grains of water.

Loaded to equal pressure, there would be little difference in velocity, however other brands of brass could vary noticeably. There was considerable difference in the empty weight of the brass though. The NE brass weighed 428.5 grains with a fired primer, and the 45-120 only weighed 360.0 grains with a fired primer. This leads to the speculation that the NE brass might be a little stronger than the 45-120, assuming equal hardness of the brass. This could be of importance, particularly in double rifles (even at the pressure levels we are dealing with) from an extraction standpoint.

I went through the QuickLoad workup, and came to the conclusion that I would feel better about keeping the 45-120 in the 2000 to 2050 fps range. This is still nothing to sneeze at, and I would have no qualms about using it on buffalo.

Jim