Home Forums Hunting & Shooting Gunsmithing Marlin 336 rechambered; has sticky chamber

Any and all advice appreciated on this problem. I had a Marlin 336Y rechambered to .307 Winchester. It shoots very well, but extraction is difficult, to put it mildly. It's so sticky that I have to put the butt on my thigh and give the lever a good yank. Naturally, I'm reluctant to shoot it much because I don't want to break the extractor. I shoot everything from 110gr .30 Carbine bullets over a very modest charge of milsurp BL-C(2) equivalent to 173gr cast FN over IMR4895 to Hornady & Nosler 170gr jacketed over 43.0gr of Varget. Every one of those loads causes hard extraction. The ejected cases have a fine. grainy pattern on the case body. It leads me to guess that the reamer wasn't the sharpest tool in the toolbox, but there may be other things I should be looking at too. If it is a "rough" chamber situation, is there a way to polish the chamber without distorting its shape? Would sizing with a small base .308 die help?

Did you pay a 'Smith for the work?

If so, bag up your fired brass and take it back, it's not your problem to diagnose or fix.

Well, yes I did. But if I ship it back and it takes as long to get it back as it did when the rechamber was done, I won't be hunting with this rifle next year. So I think I'd like to addtess it myself, if do-able.

Assuming the chamber dimensions are correct, it's probable that the chamber could benefit from a bit of polishing. There's a balance between smooth enough and too smooth when it comes to extraction, though. Not smooth enough can give issues. But so will too smooth. In between is what works...which is right around what a worn piece of 320 grit will give. In fact, many 'smiths do that as a final step after chambering.

Tough to diagnose long distance...but some food for thought.

Good shootin' -Al

Roger that. BT/DT myself.

Could he wad up some 0 or 00 steel wool on a chamber fitting cleaning brush and spin it a couple three times in the chamber with some light lube, flush it, dry it, try it, and see if it improves? Maybe take several trials to get it right? Not polish completely but take just enough rough out?

If the chamber is rough enough to cause extraction difficulty, as bad as described, there is some significant roughness, which should be readily apparent on the brass. Bad reamer or inept gunsmith. I would use a ball hone (1/2 inch) and some light oil. Power the hone with an electric drill. Keep it moving back and forth. Don't dwell in one place. Run the hone in the chamber for no more than thirty seconds. Run up until you just touch the shoulder then pull back. The ball hone will do a relatively good job of giving a smooth, straight surface, without removing too much material, but it does require some technique. It's a good idea to polish a hole which doesn't matter first; to break the hone in a bit, and get a feel for how it works.
Another system which works quite well is to use a slotted rod with a piece of abrasive cloth which is a loose fit in the chamber. Run it with a high speed grinder and work it back and forth like the hone.
Anything is best done with the barrel removed, but I'm guessing that is not an option. GD

Post some pictures of the brass. If you use a sharpie pen to color a couple cases and then fire them, the tight spots should show up as bright spots with the marker rubbed off. Have you measured brass with a micrometer at the base in front of the solid head, at the shoulder, and on the neck before and after firing? That could tell a tale as well. If the chamber is just rough and grabbing all over or has a burr, it should be a quick and easy fix. If it is a dimensional issue like a ring that the case is swaging out into, it will require a little more effort.

For doing a chamber touch up, I use a piece of 12 inch 5/16" wooden dowel and split one end to hold a piece of crocus cloth or wet/dry 320. Add a bit of light oil and proceed as GD explained. For barrels still on the gun, a longer piece of dowel works great. Clean the beejesus out of the chamber/barrel afterwards.

A good test is to lightly oil the case of a loaded round with a couple drops of Kroil, Marvel Mystery Oil, etc. and fire it. If it extracts easier, that's a good clue that a light touch up of the chamber will help.

Good shootin' -Al

How do they chamber, difficult or easily?

I'd be interested to know who did the work. I'll be sending a 336 out for rebore and new chamber after the first of the year. I've never heard of the outfit I'm using leaving something like a rough chamber though.

I'd understand if you'd not want to out anybody publicly.

I may have missed it, but have you tried factory ammo?

Just now catching up with this thread and my PMs. Excellent suggestions all...just as I had hoped The 'Fire would offer up. Every suggested test will be done and results posted. All in good time. Hunt first; fix this puppy after late muzzleloader season ends in mid-December. Thanks to you all!

I’d rather not say who it was, but I will say who it was NOT. It was not JES, who did excellent work on two rebores for me.

Roger that.

Once again, maybe I missed it, but does it do the same thing with factory ammo?

At $3 to $4 a round, I have never fed it factory ammo. I have always handloaded W-W brass...often new.

I have used the techniques described by Al and greydog, mild abrasive and electric drill, with success.

Mrchong, sending you a PM....