I've read it's a roll of the dice whether the Marlin will cycle "Spl's" reliability, some do, some don't. So I have not bothered trying "Spl's" in either of my 1894's (1894c 357 Mag/38Spl & 1894 44 Mag/44Spl). I've often wondered about accuracy with the 'long jump' to the rifling when using the shorter "over all length' 38 or 44 Spl's.
My main usages are target/gong and small game. I reload 357 Mag. & 44 Mag. using bulk Campro bullets in my Marlins, makes them fun relatively affordable shooters. I had a really nice easy shooting, fun, mag emptying load for the 357, I could hammer the gong @ 50 yards all day. BUT at 100 yards it was all I could do to hit gong shooting from bench. Grasping for straws I put the estimated muzzle velocity etc. etc. into a ballistic calculator and found the bullets where slowing down through the sound barrier (~1120 fps) at about 90 yards. Up the H110 powder charge, in the 357, closer to max and have no point and shoot issues hammering the gong 25>100 yards.
Marlin 1894c 357 Mag/38 Spl c/w Vortex 2-7*35 'Rimfire'. Bought new May 2018
Marlin 1894 44 Mag/44 Spl c/w Vortex 2-7*35 BDC. Bought new Jan 2018