I just acquired a Ruger M77 RSI in 275 Rigby. Since it only has an 18 1/2" barrel, would it be more efficient to use a faster burning powder? From all my manuals and everything I have been reading, the 4350 powders seem to be a good choice and something I have available but I can't find anything regarding the shorter barrel length. Any suggestions would be appreciated. I will be using 150 gr. bullets.
