M1 Garand gas cylinder lock fit - re-hash

[mshehan]

I've found numerous posts, mostly older, about the proper "lock-up" of the Garand cylinder lock. It made me think of a few questions that I don't think were answered. Or at least I'm looking for answers to questions that I can understand. Here they are:

- Was the rifle designed to have the lock bottom out on the chamfered shoulder of the barrel @ 6 o'clock? I just can't imagine millions of rifles having hand fitted locks. The chamfer both on the barrel and lock seem like basic machining practices.

- Does having the lock not bottom out on the shoulder make for an inaccurate rifle? It does seem that it's another positive stop in order to shore up the lock/cylinder assembly to prevent any movement/loosening. Is this a case of every little bit helps?

- I've found my lock stops @ 12 o'clock. I simply backed it off to 6 o'clock and tapped the cylinder up to the lock (from the bayonet lug, of course). I haven't considered this a final assembly until the jury returns (the fine folks in this forum). The cylinder is still snug on the barrel. I can see a possibilty that the assembly might loosen at some point, being that the cylinder friction might be the only thing holding it from moving, and there's always play in the threads.
-A note on this: It makes sense to me that if I place the cylinder far enough forward to allow the lock to move the cylinder back just enough to snug up @ 6 o'clock, should this be adequate? I read a concern about stress on the threads due to this process. I would think a properly snug (not tight) cylinder should allow the assembly the move in this way. Add the gas plug, tighten it sufficiently, and I believe you have the next best thing to the perfect fitting cylinder lock. I'm sure tens of thousands of nice Garands must be this way.

I'm sure I have more questions, just can't think of them now. Thanks all.

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[mshehan]

Update:

Just tried my old cylinder/lock/plug combo again. The cylinder is loose by itself. When I add the lock and plug assembly, and tighten it up, there is still slight movement. So it seems beneficial to have the lock bottom out @ 6 o'clock, giving another positive stop for the assembly to prevent any future movement. Problem is, at $15 a piece for the lock, it doesn't seem economical to even purchase a half dozen locks hoping that one will work as desired. I just can't imagine very many Garands are this way!!! Am I just chasing something that most don't even worry about??? I'm not a competitive shooter, I just want a nice accurate rifle. I want to be able to pop a small target at 100yds or more with iron sights and be able to say "Nice shot". Please slap some sense into me!

[browningautorifle]

It's not the gas cylinder lock that dictates the accuracy of the rifle. It's the gas cylinder. If you have zero rotation on the gas cylinder then you have accuracy. The lock just keeps it from falling off the end of the rifle. The gas vent should be in the center of the port in the cylinder. No magic beyond that. And yes, I think you'll get the phone book on this one.

[boatbod]

I'm interested in this discussion too.

My gas cylinder would need to move rearward about 1/16" if it was to come up tight against the barrel shoulder, but in that position there is no way the lock will screw all the way down before it bottoms out. By necessity the cylinder is therefore slightly forward of where it could go, but there's no way to change that without modifying something.

The cylinder doesn't rotate (it's pretty snug on the splines) so for now I'm not overly concerned about accuracy issues.

[Garandy]

This may be of interest: Fore/aft gas cylinder movement on match prepped M1

[boatbod]

Thanks Garandy! I'd seen that thread before, but re-reading it cleared up a few questions. i.e. the cylinder lock needs to be bottoming on it's shoulder, which in turn sets the position of the cylinder itself.

[jmoore]

If you aren't trying to build a match rifle, and the rifle is accurate and functions, don't get too anxious over the clocking of the lock. Esp. if the front handguard isn't permanently afixed to the barrel band. I'd rather have some fore and aft play in the handguard than not on a standard rifle, which sometimes means backing off the lock one turn.

As browningautorifle notes, it's more important to check that there's no rotational play in the assembly.

There's a fair amount of "no cost" experimentation (aside from ammo expenditures!) you can do here to see what works best with the parts you have. Sometimes a bit of mix and match does pay off, though.