7.62 M1 Garand sticky chamber

[boatbod]

i thought about this...if you have rifling marks in the cases, then chances are you went too deap..looking at your cases you have pictured, looks like you may have an issue with the reamer, never seen a case that had milling marks in them...
maybe shoot a factory round, i found that remington cases work best for test fire. they run smooth, and dont have the machine gun crimps.

I certainly can't discount a problem with the reamer since it is new, but I doubt I went too deep. The go gauge only just closes fully and the bolt lug only comes about 75% of the way closed on a nogo.

Now that you mentioned machine gun crimps, I went back and carefully inspecting some unfired rounds from the same box as the previously posted casing. Now that I look more closely I can confirm they do have faint crimp marks around the case mouth in the same 6-way pattern. Guess we can discount that as being part of the problem, especially since there are no similar case-mouth marks on cases from the Peruvian ammo that I fired at the same time. Both sets of brass do however show the same rings around the middle to rear areas, and rim damage is much worse on the Peruvian vs the commercial ammo. At this point I'm almost certain that those tool marks need to go away.

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[browningautorifle]

If your chamber's as tight as you suggest then Chucks idea of a couple of turns with a finish reamer will do it. I've done that sort of thing and barely any metal comes off. The chamber's then fresh and new and your tight chamber's no more. Just be careful. I just don't know how you can do that as carefully with the barrel installed. You need an even pressure from the rear and straight in.

[boatbod]

I have two concerns with running a regular finish reamer in the chamber:
- given that the bad area is close to the breech, any success with a reamer would require the chamber to be tight in this area, otherwise it's just going to cut at the neck and throat again. The impression I get from hand feeding fresh rounds that the rear of the chamber may already be a little on the looser side in that area.

- as you say, running a reamer with out removing the barrel doesn't sound very practical since the only way of turning it would be with a small ratchet wrench or similar. The offset forces and lack of feel would make life tricky and probably not result in good accuracy.

Oh well, sounds like time to go shopping for a barrel vise and receiver wrench.

[boatbod]

I pulled the barrel today, and was somewhat surprised that it was barely more than hand tight. Well let me correct that - my surprise lasted perhaps two seconds until I remembered that nothing else had been right with the gun, so why would this be any different...

Anyway, having gained access to the rear of the chamber I was able to lap away the circular machining marks using 800 grit compound smeared on a fired case. The case was spun with a cordless drill while being moved in/out, taking care to avoid coming up hard against the shoulder. The finished chamber appears uniformly gray, except for the shoulder which still had a few reamer marks.

After reassembly, the go gauge closed properly and the nogo didn't, so I'm confident that headspace is largely unchanged. Hopefully I'll get to the range in the next week or so to see if I've solved the extraction and cycling problem. I don't know if it counts for much, but a selection of fired cases can now be chambered and extracted without resorting to prying the bolt back. [They are still tight, as I would expect, but at least they pop out with a good tug on the operating rod.]

[browningautorifle]

Well...I still think it's not quite right, but you'll soon see. They should move in and out effortlessly. Chuck, do you want to take him through re-creating the crush factor of the barrel shank? Or lock-tite?

[Chuckindenver]

i wouldnt use lock tite.
just peen the shoulder all the way around , and youll get one more crush fit..i use the rounded end of a ball peen hammer, just work the edge of the of the shoulder all the way around.
it will give you one good crush fit.

[boatbod]

The shoulder had previously been peened with a centerpunch - a real high quality Bubba job! With nothing to loose in that department, I added to it and got the barrel to draw up tight with the front sight correctly indexed. I though about loctite, but really with to sort of temps it might reach if fired enough, loctite wasn't going to stay tight for long.

I believe the real answer is to fabricate a breeching washer and set the shoulder back sufficiently to give the correct starting index. Any idea how many degrees before center an M1 barrel should be when assembled into the receiver just hand tight?

[Chuckindenver]

a washer well ruin your headspace...a new barrel is the best fix..rolling the shoulder if done right fixes the issue.

[boatbod]

a washer well ruin your headspace...a new barrel is the best fix..rolling the shoulder if done right fixes the issue.

Headspace shouldn't change much, since the object is to end up with the barrel indexed in the same position it is now, just with more torque on the threads.
The procedure is described by Peter Laidler (http://photos.imageevent.com/badgerd...ching%20Up.pdf)

Yes, a new barrel would be the simplest solution...

[browningautorifle]

Like Chuck says, if you redo the shoulder and draw it up carefully it won't come undone nor will it ruin anything. I've done them and it works fine. Just do it correctly and leave it alone. Then shoot the pi** out of it.