I have owned a Marlin 1894-S Carbine in 45 Colt since the mid 80's and it is one fine rifle! I used it for 20 years of CAS, and 30 years for target shooting, plinking, varmints, and just blazing away with. I have shot many thousands of rounds from this Carbine and never had a jam, mis-feed, or FTF of any kind. My version has the Micro-groove rifling which was later changed over to Ballard rifling on later production rifles, but I have never had any issues with it and it is superbly accurate. Just so you know, most of the ammunition I've put through this Carbine has been re-loads that have been re-loaded "umpteen times", and some of the brass just came off of the ground at the Range. My point here is that these cartridge cases are far from optimal, yet they have all functioned flawlessly!
All I can say is I would DEFINITELY buy this Carbine again, but would NOT buy one of the versions that is being made by the new Marlin Company since they were sold and moved. I have heard nothing good about them, so if you are interested I would highly suggest buying one that was manufactured prior to that era.
Chief38