I load for the Single 7, which has a shorter cylinder than your SP101. For full boogie with the 327 case 100 gr XTP, I use 13 gr of Enforcer or AA9, both very blasty. For plinking or small game, the 100 gr MP 314-640 with 3-3.5 gr of W321 in 32 H&R is hard to beat. Same bullet with 5.5 gr of...