I had good luck with the Fed. LRMM in a 50 x 2.5" but have settled on CCI BR2 for the 40 & 44. Funny when I started this black powder cartridge journey ( that doesn't seem to end by the way ) Federal magnum primers were recommended for just about everything. As time has gone on..there has been more experimentation with 'lower impact' primers and pistol primers... apparently with varying degrees of success. Suffice to say if I can't obtain BR2's, then Federal match..either mag or standard LR would be my next choice. As Don said.. it looks like you've happened upon a key ingredient for a sweet combination. Wish we could get that O.E. over here though
J.B.