This is about the well-known problem with Marlin lever-action rifles. If you were expecting something about blues riffs or home-made preserves, you’ll be disappointed.
The carrier is the plain steel gizmo bottom centre in this image.
The Marlin Jam starts right at the beginning of the gun’s life when, even after just a few rounds, the underside of the lever (the lever cam) digs into the bottom of the carrier and creates a line.
The dreaded line.
This line worsens with time and eventually screws up the timing of the gun, with two rounds jammed together behind the chamber.
I’ve dealt with this problem a couple of times now and thankfully on both occasions with a new or nearly new gun. The procedure with older Marlins with a well-established line on the carrier is a bit more involved; it can mean more drastic measures, including a new carrier. However, you can prevent it from developing in a new gun/recurring in an older one by smoothing off part of the lever cam as follows.
Normally, the arrowed edge is quite a sharp angle. That’s how it comes out of the factory. Here, I’ve taken preventative action and put a small radius on the edge to stop further damage.
The line, it’s burred edges taken down with emery paper and the whole flat gently smoothed over with very fine emery.
The rounded edge of the lever will no longer dig into the carrier and the line in the carrier, although still present, won’t get any worse.
I’ve only used emery on the carrier. 600 grit and then 2000 grit to polish. It’s not a good idea to start attacking the carrier with anything more aggressive as removing too much metal can make a bad situation very bad indeed.
I topped off my repair with some DSX, rubbed in well, and all was good to go. Action as smooth as butter now.
DSX Assembler grease. Ideal for a job like this. I treated the whole action with DSX before reassembly. Well worth doing.
I love Marlins, but this one thing rankles with me a bit. It probably affects their bottom line too much to warrant fixing this issue, but these are good rifles and shouldn’t be allowed to leave the factory with this decades-old gripe still present.
Anyway, that’s how it’s sorted. There are numerous YouTube videos showing this in a lot more detail, but the above is how I fixed it.