Marlin 336 Bolt Pin Siezed

[Scout21]

I need to replace the firing pin in my 1957 Marlin 336 S.C. I doubt the bolt has ever been disassembled as I'm having a serious issue with it's disassembly.

I've managed to get the front pin out with relative ease, however the pin holding the rear firing pin in is siezed in place. I removed the front pin from the bottom of the bolt through the top as instructed in a YouTube video.

The rear pin is what's giving me issues. I've beat the hell out of it with a steel pin and brass hammer to no avail. I even reluctantly used a steel hammer, no dice.

I've soaked it in WD-40 overnight as well as boiled the bolt in water in hopes it would help loosen the pin up.

The front pin doesn't seem to be tapered, so I would assume the rear one would also not be tapered. The pins are solid, however I've seen in some videos that people have bolts with roll pins. I'm curious if my pins are replacements. The seem to be stock and original, but I could be mistaken.

I'm at a loss here, I may just need to drill them out. I'm reluctant to do that until all options are exhausted, though.

 

[beag_nut]

A roll pin can be instantly identified by looking at its cross-section, even when installed. Even a split-pin can easily be seen. Drilling out either would be close to impossible due their hardnesses.

 

[Kp321]

Forget the WD-40 and soak the pin with Kroil or ATF/acetone., for days.

 

[Scout21]

A roll pin can be instantly identified by looking at its cross-section, even when installed. Even a split-pin can easily be seen. Drilling out either would be close to impossible due their hardnesses.

Of course. What I was suggesting is that the bolt may have originally come with roll pins, but have since been replaced with improper pins, leading to the siezed pin. I believe they are original, though.

 

[Blue68f100]

Might want to try some Hot/Cold cycles, may help loosen it up. Use Kroil or the ATF/Acetone mix in a Ultra Sonic cleaner. May take a while but it's worth a try. If you US cleaner can heat up the solution crank it up and go after. Use deep freeze for the cold cycle.

 

[Scout21]

Use deep freeze for the cold cycle.

Didn't think about freezing it. Good idea!

 

[edwardware]

. . . the pin holding the rear firing pin in is seized. . .

- Letting some Kroil, or ATF, penetrate might help.
- Heating 'till the Kroil fizzes into the gap will help
- Freezing might. . .
- Hammer material only matters if you hit the work. Punch material matters. You want steel on steel, and you do want a nice sharp strike.
- Don't assume it's not tapered, measure.

You are probably not striking hard enough to get it started. The danger is that you probably are striking hard enough to peen the pin tighter into the hole.

If you can't drive it, you can drill it. Use an undersized bit, in a drill presss, with good workholding (a clamp or two), and cutting oil.

 

[Scout21]

The danger is that you probably are striking hard enough to peen the pin tighter into the hole.

This is what I was terrified of.

Don't assume it's not tapered, measure.

I would if I had access to calipers. Regardless, if the video I watched was correct then I should be hammering in the correct direction. The front pin came out with little effort in the same direction, so I would assume the rear pin should as well.

 

[Blue68f100]

Use a short starter punch, less likely to move, stiffer due to it's only has a 3/8"-1/2" shaft. Use a big hammer (2 lb sledge). Sig's have a pin in there 229's that requires a special punch and a 2# hammer to get it to move. Make sure the part is supported solidly so the energy is transmitted to the pin. This goes a long ways in removing hard to move pins. The next best thing is a press. Some guns mfg puts sights on their guns using a Hydraulic press. So when it comes time to move it it takes a good solid setup.

 

[Scout21]

Make sure the part is supported solidly so the energy is transmitted to the pin.

I'm having trouble with this as the bolt wants to roll around when I strike it due to the pin being offset. It isn't centered directly on the center axis of the bolt. I tried using my vice padded with denim jeans, but it still wants to shift around.

 

[Blue68f100]

Your going to need V blocks to grip it and then add a support underneath to make it solid. A barrel vice would work if you have one.

The use of rosin will keep it from spinning.