Dido's to what Trailrider posted. I have a 22 LR Marlin Mountie that I've had since '69 (paid the high cost of $92 for it), I've shot both jacketed and plain lead bullets through it's micro-groove barrel with no difference in accuracy, but that's shootin a 22 vs a 44. From what I've read, heard, and expierenced, as long as you stick with hard cast bullets and smokeless powder you should be ok. Black powder would foul up the rifling bigtime. You'd problably be ok with softer lead also as long as you kept your velocities below 1000 fps levels, just hav'ta try and see! Do you or your wife plan on shooting 44 Mag or 44 Specials through it and would kind of loads? Reduced loads in either caliber with softer lead (not cap and ball soft) and smokless powder shouldn't cause any leading or fouling problem esp with some of the newer cleaner burning powders. Try 44 Specials in it and see how they cycle. My Marlin 357 Cowboy does just fine with 38 Specials and if you don't plan on shooting/loading full house 44 Mag lds, the 44 Special cases will result in less air space in the cartridge for reduced loads. Good Shootin"" Yers, Crow Choker