Marlin Model 43 Shotgun

The Model 43 was produced by Marlin Firearms Co. from 1922 until 1930. It was made in 12 gauge only and the serial numbers ranged from 537 to 17411. The 22XX serial number on this shotgun indicated it was assembled in 1923. The Model 43 is one of the more complex firearm designs that I have seen. This one had been worked on at sometime in its life as several of the screw heads were damaged and there was a big scratch on the side plate. The receiver was dinged up next to the barrel locknut.

This one is not a collectible, but it’s unfortunate that people don’t use care and the proper tools when working on a firearm. Disassembly Make sure the magazine and chamber are empty. Removing the stock first makes it easier to work on the shotgun. Remove the buttplate and use along, straight-blade screw- Cartridge release button is above the ejection port. Release lever retaining screw location is next to the ejection port. driver to remove the stock screw.

Remove the trigger assembly screws—two on the left side, one on the right side, and one on the bottom, behind the trigger guard. The screws are different sizes, so keep track of where they go. Slide the trigger assembly out of the receiver. I sprayed the trigger assembly with solvent, scrubbed it with cotton swabs, and then dried it; I did not disassemble it. Far Sear (hook shaped part) is right of the hammer. The safety is in front of the trigger.

Far Cartridge release lever is located next to the magazine tube. The cartridge cutoff is in the front of the side plate. Ejector tab fits in groove in the bolt. The bolt locks into the recess at the top of the receiver. Bolt assembly shown at bottom of photo. Remove the slide release lever from the bottom of the left side of the receiver. It pivots on a pin and has a spring that fits into a slot. Push the slide to the rear to retract the bolt. The side plate screws and side plate are removed.

The side plate has a tab that fits into a slot in the top of the receiver. This tab must be inserted into the receiver first when the side plate is installed during reassembly. The side plate has a small cartridge cutoff lever at the front; it did not need to be removed. The carrier retaining screw and carrier are removed. Push the bolt and slide forward about half of its travel so the bolt assembly can be lifted off the action Tube must be lifted slightly to loosen the screw. bar pin and out of the receiver.

Carefully set the bolt assembly aside for now—cautiously, as it can disassemble itself if you’re not careful (we’ll get to the fun part later). Remove the ejector (small leaf spring) from its recess in the left side receiver wall. It is retained by a screw. This spring must be compressed slightly to reinstall the bolt and makes life a little more difficult. The small tab fits into a groove in the bolt. The cartridge release has an external button on the left side of the receiver.

The button pushes on a springloaded lever that pivots on a small screw on the bottom of the receiver wall. An eyeglass screwdriver is required to remove the screw. All of this results in an empty receiver that is easily cleaned. The magazine tube and slide are removed by first squeezing the latch on the outer plug of the magazine tube and pulling it forward until the detent button on the inside of the tube pops into its hole.

The screw that holds the tube to the barrel is now visible and can be re- Latch on the outer plug engages the slot on the inner plug to retain the tube in the operating position.

Forend nut is on lower left. moved. This screw is retained by a smaller screw so the magazine tube must be lifted slightly while loosening or tightening the barrel screw. The action rod slides in a guide on the magazine tube band on the bottom of the barrel; this band supports the receiver end of the mag tube. The band is dovetailed to the barrel and it is pushed to the right to make room for the action rod to slide through it. The outer plug is retained in the mag tube with two screws.

After it is removed, the inner plug with the barrel screw and detent button can be removed along with the spring and follower. The slide is removed from the mag tube by removing the forend nut on the front of the slide and pulling the tube out of the slide. I cleaned the inside of the magazine tube and slide with solvent The operating rod pin rides in the slot in the link (lower left). Bottom, link and locking latch. on a paper towel rolled into a cylinder and pushed through with a wooden dowel.

I followed this with dry and lightlyoiled towels. The barrel is threaded into the receiver with left hand threads. No interrupted threads here. The lock nut on the barrel is a split ring design. The small screw on the lock nut is loosened and the nut is rotated slightly counterclockwise (looking from the muzzle). This allows the receiver to be removed from the barrel by rotating it clockwise.

Bolt Disassembly/Reassembly The bolt assembly is comprised of five major components: breech block, bolt, locking latch, link, and guard plate. The breech block contains the front firing pin and the extractors. The bolt pivots on the breech block and contains the rear firing pin. The locking latch and link are held together by the spring-loaded pin in the latch. The guard plate pivots with the bolt and acts as a dust cover. The locking latch and link are easily removed from the bolt.

The latch and link are retained on the bolt by the round pin in the center of the link and the end of the latch that sets on the end of the bolt opposite the breech block. That end of the bolt has a groove on the side that the end of the latch seats on. The breech block, bolt, and guard plate are disassembled as follows.

With the breech block pointed to the right and the guard plate facing up, the bolt is rotated clockwise 90 degrees relative to the breech block (the rear firing pin needs to be pushed away from the breech block). The bolt and guard plate are

lifted out of the breech block. The guard plate is then rotated 90 degrees counterclockwise and lifted out of the bolt. The front firing pin is not retained in the breech block and can fall out. Reassembly of these parts is the opposite of the disassembly. The latch and link are assembled with the latch spring pin seated against the link. The round pin of the link is inserted into the bolt and the tapered pin inserted into the slot on the end of the bolt (the firing pin is pushed to the rear for this).

The end of the latch is pulled onto the end of Stock Repair The stock was cracked on both sides, starting at the receiver and extending about 2" in length from the outside into the center hole. I drilled a small hole in the center of each of the cracks, about 1.5" long, following the angle of the cracks. I forced glue into the cracks with a small diameter dowel until the glue was visible on the outside of the stock along the full length of the cracks.

I used heavy rubber bands to compress the cracked areas, wiped off the excess glue, and set the stock aside for 24 hours. Shotgun Reassembly After thoroughly cleaning all the parts and applying a little oil where the bolt by compressing the spring and the end of the latch sets on the groove on the rear of the bolt. When the bolt assembly is installed in the receiver, care must be taken to not dislodge the end of the latch from the bolt. needed, I started the reassembly.

The barrel is installed on the receiver (left hand threads). I left the lock nut loose until the mag tube was installed into the receiver to ensure alignment. The mag tube is American Gunsmith Reader Services 1.

Far Breech block contains front firing pin. Bolt contains rear firing pin. slid into the band on the rear of the barrel. The action bar fits through the slot on the band. The barrel screw is tightened while lifting the mag tube slightly. The detent button on the mag tube is depressed and the tube pushed fully into the receiver. The latch on the outer plug engages the slot on the inner plug and locks the tube in position.

The barrel lock nut is tightened (clockwise direction) against the receiver and its screw tightened. Install the cartridge release button, lever, and screw. Install the ejector and its retaining screw. Slide the action bar to the rear of its travel. Place the bolt assembly at the rear of the receiver. This gets it partially behind the ejector which pushes up on the bolt assembly and makes assembly a little more difficult. The ejector fits into the slot on the bolt so the bolt must be aligned with the ejector.

The action bar is moved forward until its pin fits into the slot on the link. Pushing down on the bolt assembly helps to line up the parts. Install the carrier in the receiver, the pin on the link fits into the slot on the back of the carrier. The bolt is pulled forward slowly until closed with a little downward pressure on the bolt to keep the pins engaged. Install the side plate and its screws. The tab on the top of the side plate must be installed first.

Install the slide release lever on the pin on the inside of the receiver and push its spring into the recess. The trigger assembly is slid forward into the receiver, the sear hook fits under the carrier lever (shotgun inverted). Start all the screws and then tighten. Install the stock and buttplate. Perform a function check with snap caps. Compared to more modern shotguns, pump or semi-auto, the Model 43 design seems overly complicated for its purpose.

The machining of the receiver and the complex bolt assembly, along with the magazine tube assembly, increases cost when there are simpler, less expensive, ways to do the same function. Whatever the reasons, this was an interesting project to work on. AG Far Rear firing pin is protruding from bolt.