Picked up a new to me JM stamped Marlin 1895SS. Beautiful gun, 98% condition... has been fired but very little. Took her to the range tonight and using hornady and buffalo bore ammunition, the gun would not feed a single round.

Sometimes the rim gets stuck in front of the ejector. Sometimes the shell will feed 1/4 of the way into the chamber, like it isn't being lifted enough, and other times the round will get stuck half way out of the magazine tube and you have to use a screw driver to pry it out into the chamber.

Pretty disappointed considering how nice of a gun this is.  Trip back to Marlin or something I can fix myself?

Are you working the lever slowly?

Tried slowly, medium fast, and as fast as possible. Same failures.

I have two other Marlin 45-70s...never had any issue.

Hornady FTX? My guide gun eats everything from buckshot to Garrett Hammerheads, but it chokes on Hornady every time.

how old is it, the tube spring may not be pushing cartridges out with enough force.

May be dirty and not allowing the parts work together.

Lifter dropping far enough to pick up a new round.

Tighten the screw on the side of the receiver. If it's too tight. loosen it. That's your problem.

The magazine follower is what is causing this. New style is dimpled to capture the point of the Hornady. Old style is flat and caused your jams. If it's a JM the most likely has the flat. Just get a new correct follower and that should fix. Get a. New spring too while at it. I went thru this and it's a pain to clear a jam in a lever.

Step one for most feed issues, clean the darned thing.  It doesn't matter if it's new or a hundred years old.

Step two, inspect the feed tube for damage.

Step three, tighten all screws.  Again it doesn't matter if it's new or old.

Step four, if it has a plastic follower, usually only new guns, replace it with a steel one as God and the two John's intended.

Step five, replace the spring.

Honestly if this doesn't do it, it's time to find a smith who knows lever guns.  Sometimes they need a bit of fitting or rehab of the receiver and it's associated parts.  Unless you know what you are doing, I'd suggest hiring a pro.