I have a 444SS circa 1989 Marlin with the Micro-groove rifling in a 22" barrel. Cast bullets are not recommended, but as long as I use jacketed stuff I am alright, which is what Marlin optimized the rifling for. I chose the .444 prior to the huge resurgence in popularity of the .45-70 because it held one more round than the 1895SS, had a flatter trajectory and came in two bullet weights commercially, 240 and 265 gr. This appealed to me because I could hunt deer with both my .44 mag and .444 both loaded with 240 grainers, however the problem is that 240 is not the optimum weight for the .444, and 240 gr. handgun bullets pretty much come apart when fired in the rifle.
It wasn't until fairly recently that folks figured out that something on the range of 300 grains in the .44 would be almost ideal. That requires careful handloading, and for some idiotic reason the 265 gr. is no longer offered commercially, leaving only the 240.
Marlin made the switch to ballard cut rifling in the .444 a few years ago, so now folks can take advantage of hard cast bullets.
If I had it to do over again I would get a new .444 Guide Gun and see if Garrett cartrdiges or someone else could load me a hard cast 300 gr or 320 grain bullet which would just kick a%s on anything up to elk, if you got within 150 yards or so. I still feel the cartridge is as good as the .45-70, and does not kick as much. It just does not come in as many variations currently.
In any case, my .444SS is the model without the current stamped checkering. I added an Uncle Mikes recoil pad, a Weaver fool-proof peep sight and replaced the aperture with a Merit adjustable disk so I can crank it big or small depending upon the light. Finally replaced the carry strap with a nice heavy Competitor + sling from Brownells. One of my favorites.
Sorry for the long-winded response, but I was a gun nut long before I discovered knives or the new wonders of big shiny curved blades!
regards,
Svashtar