I've had 94s in that jammed as well. The action would be locked up with a case still in the bolt and the tip of the bullet in the front of the ejection port. I don't know if they short stroked it or what? One fellow brought his in a week or so later with the same problem. His bullets specked out right. I just trimmed a little off of the front of his ejection port, reblued and gave it back to him. I personally couldn't get it to jam, just guessing he wasn't coming all the way down before going back up. None the less he never brought it back again. The second time was free and I let him know if there was a 3rd time it would be free as well so he'd of probably brought it back if he had any more trouble out of it.
Both lever actions were highly popular here until the magnum craze. Can't say that I worked on more than a dozen in my life so I wouldn't worry to much about either having serious problems.
I'm really not worried about problems per se. The question is more about design attributes than anything else. The pure engineering plusses and minuses, if you will.
Clearly both designs have served 100+ years and 14+ million units worth of riflemen, LOL! I guess that's one reason why I like them.
As for magnums... never really felt the need in rifles. In handguns, yes, because they are inherently less powerful in most cases. So definitely in revolvers I go for the .44's and .357s... planning on a .454 Casull when I find a NIB SRH that I like. In rifles, 06, 45-70, 30-30, 7.62x54r, 8mm... all good enough for me. Do admit to liking the .458 Win. Mag though. There's just so many capable cartridges... more than I could ever get to in one lifetime.
Anyway, the most common cause I read for the "Marlin Jam" was wear between the cam on the lever and the carrier... so easy fix seems to me... if it happens to wear that way... hard face the cam and shape it... embed and silver solder a hard metal insert into the carrier. I imagine the cowboy action shooters have some sort of durability and "slickness" mods they do.
Som wouldn't want to have to, but not really worrying about it. Seems like a simple thing to correct. Though I have to admit, if it came really out of time... unlike an SAA, I really couldn't at the moment, begin to figure out what would have to change. Will have to disassemble it a few times and look it over, do some reading.
So I guess it's really just a gun buff question.
One thing do wonder about though, is the cam surfaces between the hook on the lever and the bolt stop/lock (not sure what it's called). Since the lever moves in an arc... down and around... I could see those surfaces wearing in way that would let the lever slip off without fully pulling the stop down.
Maybe not, I'd have to sit down and work out the geometry to really know how much it would take.
It's an interesting design point to be sure... gets rid of the need for a linkage of some sort. Just wondering if the tradeoff is reduced service life.
In a similar vien, I have to wonder if... the bolt stop lets go... does the lever essentially try to break your fingers, if not sever them?
Perhaps unlikely, but it does strike me as a possibility.