Introduction

Ever since getting into Cowboy Action Shooting, I have been totally infatuated with lever-action rifles.  I have several Marlins in my collection:  an 1894 CB in .45 Colt, an 1895 CB in .45-70, a 336 in .30-30, and a 39A in .22 S/L/LR.  All but the 39a have the same action.  The 336 and 1895 have an internal round bolt, and the 1894 has an external “square” bolt.  The round bolt receivers are stronger because the rear of the receiver is closed, whereas the square bolt receivers are open in the rear to allow the bolt to cycle.

There have been many comments in the gun forums about how this action functions, some of which disagreed with each other.  So, I decided to find out for myself how this action worked.  This way I could see what areas I needed to polish and be able to troubleshoot any problem that may arise.

The photos in this article are for my 336, but the description of the cycle applies to most, if not all, big-bore Marlin lever-action rifles.  It is difficult to see how the parts interact when installed in the rifle, so I drilled two holes the proper distance apart in a bench block to mount the carrier and lever.

There are two different types of levers depending on when the rifle was built.  A pre-1985 lever is flat with two large bevels on the right side.  The 1985 and later lever has a large slot milled on the right side with two small bevels.  I’ve tested both in my 1976 336 and they both seem to function properly but using a 1985 lever in a pre-1985 rifle should be checked and installed by a competent gunsmith.

Carrier Rocker

The carrier rocker sits in a groove milled into the carrier and rotates on a pivot pin.  There is a small spring underneath the rocker to hold it out and against the lever.  Target Suite has an excellent YouTube video on how the lever and carrier interact.  https://www.youtube.com/watch?v=nWVUaa3iAcM

The hook on the end of the rocker causes the carrier to move up so the bolt can feed a cartridge from the carrier into the chamber.  The rocker pivots so the lever can slide over the hook when the action is opened. 

There are two lips or ledges on the carrier; the lip on top where the rocker rides prevents the cartridge from traveling any farther onto the carrier, and the front edge of the lever presses against the lip on the front left to force the carrier down at the end of the feed cycle.

The Action Cycle
The four main parts that control the feeding of the cartridge from the magazine tube to the chamber are the lever, carrier, bolt, and loading gate.  Yes, the loading gate serves an important function. 

With the lever closed, the front edge of the lever holds the carrier down, the bolt is closed, the bolt lock is up and held in place, and the top of the lever and bolt lock keep the bolt closed.  The lower bevel of the lever holds the next cartridge rim against the front notch in the loading gate preventing it from moving further rearward, which facilitates loading another round through the loading gate.  Without the loading gate in place there is nothing preventing a cartridge from being pushed out of the magazine tube.

When the lever is opened, during the first 3/4-inch of travel, the bolt lock is drawn down from the bolt, the lever is unlocked from the bolt lock, and the cartridge is allowed to move back onto the carrier.  If the lever is closed at this time, the bolt lock is raised to the locked position, the hook in the lever is locked into the bolt lock, and the cartridge is moved forward by the lower bevel on the lever so the rim of the cartridge is again visible in the front notch of the loading gate.  This permits the magazine tube to be topped up.  As the action is opened, the lever approaches the rocker hook, the bolt opens and moves to the rear, and the cartridge continues moving onto the carrier pushed by the magazine spring and controlled by the front edge of the lever.  The cartridge case head rides on the front edge of the lever during the open half of the cycle.

Towards the end of its travel, the lever rides over the rocker hook which pushes it down against the spring.  When the lever reaches the fully open position, the spring under the rocker pushes the rocker out so the hook at the end engages the front of the lever.  A cartridge is now completely on the carrier and is ready to be fed into the chamber. 

A small cam on the right side of the lever strikes a lobe on the bottom of the carrier that moves it up about 1/4-inch to block the next cartridge in the magazine tube and prevent it from feeding.  If the carrier does not move up to block the next cartridge you can get the dreaded “Marlin jam”, which is a double feed.  The next cartridge in the magazine tube feeds onto the carrier, but since there is a cartridge already there, part of the second cartridge is on the carrier, and part is still in the tube effectively preventing the carrier from rising and jamming the rifle.

This can be caused by either a worn cam on the lever, or a notch worn on the bottom of the carrier by the sharp edge of the cam.  To prevent this from happening, the sharp edge of the cam should be slightly rounded so it won’t dig a groove in the bottom of the carrier.  If the groove is already there, it can be welded up then filed down, a hardened shim made from a hacksaw blade can be soldered over the groove or replace the carrier.  If the rifle is used for hunting and occasional shooting, this problem may never occur.  But an 1894 model used for Cowboy Action Shooting may see hundreds, if not thousands of rounds.  It’s best to round that edge to prevent the problem from happening.

When the action is closed, the rear of the carrier rocker hook rides along the front edge of the lever which causes the carrier to rise.  This aligns the cartridge with the chamber.  As the top of the lever moves forward, it pushes the bolt forward which begins feeding the cartridge into the chamber.  The cartridge is now under control of the bolt.  The tongue at the bottom of the carrier prevents the next cartridge from being fed from the magazine tube.

When the carrier rocker hook reaches the bevel in the bottom of the lever, the lever slips off and over the hook.  By this time, the cartridge has started into the chamber.  The bolt continues moving forward pushing the cartridge into the chamber.  The next cartridge in the magazine tube prevents the carrier from falling.  If this is the last cartridge, the carrier is free to fall, but as mentioned before, the cartridge has already started into the chamber and is under control of the bolt.

The front of the lever contacts a lip on the front of the carrier and forces the carrier down if it hasn’t already fallen.  The bolt moves into the closed position and the bolt lock moves up into the locked position.  When the carrier is pushed down the next cartridge is fed from the magazine tube until it contacts the bottom bevel on the lever which holds that cartridge in place against the loading gate ready for the next feed cycle.

Comparing the two levers, it seems that on the 1976 model the carrier rocker hook rides along the side of the lever until the lever gets into the fully open position.  Then, when the hook reaches a bevel on the bottom of the lever it is pressed in so it again rides against the side of the lever.  The bevel on top of the lever depresses the rocker during the opening cycle, and the bevel at the bottom disengages the hook curing the closing cycle and forces the cartridge case head against the notch in the loading gate.

The 1985 lever has a channel milled in the side.  During the opening cycle the hook rides it this channel thereby reducing stress and wear on the hook.  Again, the top bevel depresses the rocker during the opening cycle, and the bottom bevel disengages the hook during the closing cycle and forces the cartridge case head against the notch in the loading gate.

The bottom bevel controls the timing of the carrier; it determines when the rocker hook disengages from the lever during the closing cycle.  When the hook reaches this bevel, the carrier is free to move down, but the next cartridge in the magazine tube pressing against the front of the carrier keeps it up until the front of the lever strikes the lip on the rocker and forces it down.  If the magazine tube is empty, there is nothing preventing the carrier from falling.

Polishing

If you refer to my article Building a Backpacker “Scout” Rifle you can see what areas I already polished on my 336.  Based on what I discovered with this article I did a bit more polishing on the lever.  Before polishing I covered all the areas with a blue marker where the cartridge and/or carrier made contact with the lever so I could see the wear marks.

1.    I polished the right side flat with a 220-grit stone to remove the tooling marks, then finished with a 320-grit stone followed with 600-grit wet/dry sandpaper.

2.    I polished the bottom edge (where the cartridge head and rocker hook ride) with a 320-grit stone, then finished with 600-grit wet/dry sandpaper.

3.    I gently polished the bevels with a Cratex bit and my Dremel tool.

After polishing all the surfaces, I cleaned the exposed bare metal with acetone, then cold-blued the entire top of the lever with Brownell’s Oxpho-Blue.  I heated the top of the lever with a heat gun, then applied the Oxpho-Blue with a large cotton dauber.  I kept the metal wet with the dauber for 60-seconds, then wiped off the excess liquid with a paper towel.  I used 000 steel wool to card the metal, then finished with a coat of gun oil.  I reinstalled the lever into the rifle and cycled some dummy rounds to ensure the rifle functioned properly.

Summary
This exercise showed me exactly how the Marlin action works so I could continue to polish those areas where metal contacted metal.  I did the same exercise for my Ruger Redhawk (refer to my article Performing an Action Job on a Ruger Redhawk) so I could see what areas needed polishing for an action job.