I have a Ruger Deerfield Carbine and the rifleing twist rate is one turn in 20 inches, the same as the Winchester 94 carbines. The rate for the Marlin 94 in 44 Mag is one in 38 inches.
I also shoot 180 gr. loads from both my Deerfield and Win 94 Trapper. Usually UMC 180 gr. jacketed soft-points. Very accurate and devestating on white-tails.