M1A gas system question

[LooseGrouper]

I took my M1A SOCOM out shooting this weekend and when I got back home and started cleaning, I noticed that the nut on the top of the gas tube was loose. Since I'm new to the M1A game, I have some questions:

1) What is the proper torque for this thing? Can I hand-tighten, or do I need to use a wrench to get the proper effect?

2) Do they tend to shoot loose on a regular basis? If so, how loose can it get before it starts to affect reliability/safety? (just for reference, when I say that it was loose, I mean that it could be easily turned by hand. It was still seated flush, and no threads were visible)

3) Since the front sight is held stable by the gas tube/nut (on the SOCOM at least...don't think it applies to other models), to what degree does a loose nut affect zero? If you take the nut off to clean the gas piston, etc, does the sight reliably return to zero?

Thanks in advance for the help.

LG

 

[Dienekes]

Although I have handled a SOCOM I don't remember much about its gas system. However I have used the M14 in the past and own an M1A now. I suspect that most of this will relate.

The book says to torque the plug to 27 inch-pounds. The GI manual says not to exceed 1/2 turn past bottoming (seems like too much to me). Since I do not have an inch-pound wrench, here is what I do. I apply some anti-sieze compound (at auto parts stores) to the threads, bottom it, and snug it down with what feels like about 10 foot pounds torque--think spark plugs in an aluminum cylinder head. Trial and error; better to have to retighten it now and then until you know what your particular rifle wants.

There is a gas cylinder wrench made for the standard M14/M1A to avoid putting stress on the cylinder splines. Brownell's, etc. Not sure if it will fit the SOCOM setup, though. My plug is a 3/8" hex; the GI cleaning kit handle fits it.

In my experience there is a bit of a learning curve to find out what torque your rifle wants to stay tight but not be excessively tight. When you establish that I would recommend you mark the plug rim and the cylinder body with a white paint (or even fine scribe) line. Makes it easy to "see" if and when the plug is loosening.

There is no pressing need to disassemble and clean the gas system each time after firing. On the M1A, if you lock the bolt back and if the piston will slide back and forth when the muzzle is tipped vertically and then straight down, it is moving freely enough. I put a couple of drops of GI bore cleaner (or Ed's Red) into the small vent hole in the bottom of the gas cylinder to keep things moving. I suppose I actually pull the piston once every 300 rounds at most.

BTW don't use anything remotely rough or abrasive on the piston; discoloration is normal and ok. After a lot of rounds the recesses of the piston and plug will carbon up and you should clean them out with the properly numbered drill bit sizes.

As long as I'm typing, will mention greases. Lubriplate 130-A is the old M1 standby and good; any decent auto chassis grease works fine; and lately I went to Militec grease (not the oil).

Hope you like your SOCOM; if it's as good as my M1A has been you have a winner.

 

[30Cal]

15ft lbs +/- 2lbs (some of the comp teams shoot with upwards of 21ft lbs on the gas plug). If you use a GI combo tool, it's tought to overtorque the nut. Make sure you support the rifle at the gas system and not the stock when you torque the nut (it loosens the stock fit and gas system). I like to use anti-seize on the plug, otherwise you'll need to soak the nut in penetrating oil overnight to get it loose again.

Easiest way to make sure it's tight enough is to paint a witness line before you loosen it so you know how far to tighten it when you go to re-assemble.

Sometimes, reproduction plugs will just chronically shoot loose. The GI plug has a raised diamond knurl on it. The repro one does not.

A loose plug will cause accuracy problems unto itself, and not so much due to it's relationship to the front sight. Not really a zero shift, just big groups/stringing. It will very likely cause the rifle to short stroke (bolt closed on an empty chamber).

 

[LooseGrouper]

Thanks for the help. Looks like I need to buy a wrench before I go shooting again.

It's also good to have an excuse for how poorly I was shooting. I just keep living up to the handle.

LG

 

[Onmilo]

Get a gas cylinder lock wrench from Brownells or Fulton or Amherst Depot, wherever and use a 3/8" box end on the gas plug.
You will know you have the whole system tight enough when you need both wrenches and it takes a bit of ugh-rumpff to get the pieces apart.

P.S. actually, if your rifle still has the cast gas cylinder lock Springfield seems so fond of using, get your lock wrench from them.
That goofy Springfield lock is about .060 oversize and a USGI wrench won't fit.

Better idea is to replace the Springfield lock with a USGI or a Smith Enterprise timed lock which is what I did with my rifles. HTH