M1 Garand Gas Cylinder & Accuracy

[plevniak]

I was cleaning my newly purchased CMP M1 rifle the other night and I removed the gas cylinder from the barrel. The Springfield Armory instructions indicate that I should NOT have done this. I was on a roll doing the disassembly and failed to notice this instruction. The manual indicates "this can loosen the fit and degrade accuracy."

Well I've done it. But I don't know how to reseat the gas cylinder so it won't wiggle/move. What is the proper way to secure it? By the way, it was shooting quite a bit (about 6-8 full clicks) to the right and required about 27 clicks from zero to hit a center on an NRA high power target at 200 yards. These adjustments seemed a bit extreme for me, an admitted newbie to this rifle.

I'd like to secure the gas cylinder and and hopefully restore the sights to a more "centered" zero. Answers and tips appreciated as well as a constructive "don't do that" admonishment here and there.

Thanks.

 

[Devonai]

I have only one bit of insight to this: Your gas cylinder will tighten up eventually after live fire. I removed mine and it took about 100 rounds before it was nice and tight again.

 

[Houndawg]

Removing the gas cylinder isn't going to hurt it. When you put it on, just slide it on, screw on the lock until it starts to snug. If it goes on too far, just back it off to line it up with the cylinder. If it snugs up short of lining up, then you might need to get a lock wrench made just for this purpose. Once you get it lined up, look inside the gas cylinder, the gas port should be roughly centered in the square cutout in the cylinder. Screw the gas lock screw in and tighten it down fairly tight. A combo tool will be the best tool for this since the bit is the right size for the slot in the screw. You'll notice that, if you had to back the lock off to get it lined up, the cylinder will pull forward when you put the screw in. This is the way it's supposed to be.

Your rough sight adjustment is with the front sight. Center the windage on the rear and adjust the front sight when you sight in the rifle. Use the rear sight for adjustments as needed when shooting.

Some people peen the grooves in the barrel so the cylinder is tighter, but that's probably not necessary.

Removing the cylinder is part of normal periodic maintenance of the rifle. If it wasn't meant to be removed, Uncle Sugar wouldn't have given his troops a means to remove it by issuing a combo tool. Which Springfield manual told you not to remove it?

 

[Devonai]

The SA manual reprinted in Jim Thompson's The Complete M1 Garand also advises against removing the gas cylinder.

 

[Houndawg]

FM 23-5 says you can remove it. You need to remove it to clean it properly.

 

[Khornet]

Actually,

you don't need to remove it for good cleaning. Just remove the gas plug and op rod and run a .45 brush through.

And most M1 accuracy authorities ( which Uncle Sam is most definitley NOT) make a big deal about stabilizing the fit of the gas cylinder by one means or another. Once an expert has accurized your M1 he'll tell you to leave that gas cylinder the heck alone.

 

[DMK]

I think the cautions are just to keep you from removing it everytime you clean thereby making it loose. You could remove it occasionally with no ill effects. Of course, if it's already loose then it's a moot point.

IMO, I think removing the action from a tight stock evertime you clean it will affect accuracy more. Because the action clamps on to the wood, it can loosen up and allow the metal to move around in the stock every time you fire it.

I'm usually borderline fanatical about keeping my weapons spotless, but my Garand just gets the boresnake and a wipedown after shooting. I'll probably do a full field strip around 1K.

 

[VG]

By the way, it was shooting quite a bit (about 6-8 full clicks) to the right and required about 27 clicks from zero to hit a center on an NRA high power target at 200 yards.

Is the front sight centered right now? 6-8 clicks is pretty normal for windage. 27 clicks up at 200 yards is a lot.

Ideally, you want to turn the gas cylinder locking nut until it snugs up at around 4 oclock, just allowing you to tighten it to 6 oclock and put the gas plug in. Many M1 owners keep 3-4 gas cylinder locks just to get that nice tight fit. But it's not the end of the world if you don't.

It's no big deal to take the gas cylinder off.

 

[plevniak]

Thanks for the comments

Wow. I love this newsgroup. Lot's of good information here.

I haven't had the opportunity to take it to the range again yet. So, I don't know how it is going to perform. I'll try again to get the better fit on the gas cylinder lock. I'm going to attend a local "M1 Clinic" in a couple weeks so I'll get an hands-on inspection/reassembly there. I'm a little afraid to put any torque on the gas cylinder lock since I don't have any first hand experience with the M1.

One last question. If 27 clicks is too high, how many clicks should I be at for the 200 yd NRA high power target? Assuming the top of the front sight is at the bottom of the black target center. Umm, of course.

 

[Badger Arms]

I think there is some confusion here. Are we talking 27 clicks of WINDAGE or ELEVATION? If it's 27 clicks of windage, you have a problem. 27 clicks of elevation is a different story. Sounds like you are only 6-8 clicks off for windage which is normal, although it's a good idea to get a mechanical zero so you can reset your sigts if you get mixed up on where you are. Maybe a paint line or something like that.

 

[plevniak]

Elevation

27 clicks - elevation. What's the norm?

 

[Backwoods]

I just checked both of mine and came up with 9 & 10 clicks from full down to the 200 yd mark. Both my rifles are in the black at these settings, 27 clicks seems a bit much to me.

Does your front sight appear to be unmodified, can you look at one that IS as issued? A cut down front sight would shoot high which is opposite of what you have. Darned if I can figure out what's up with this!

Don in Ohio

 

[30Cal]

If your gas cylinder is tight, then playing with it will only make it looser. If it's already loose, then it probably doesn't matter. The front sight sits on top of it, further meddling w/ your accuracy. In general, it doesn't need to be cleaned every time.

Uncle Sam's manual was written for guys who wade through surf before reaching their firing point. He also issued a segmented steel muzzle rasp which was to be used as a cleaning rod. I take the field manual with a grain of salt.

As far as your elevation, 3 things. Check the tension of the rear sight first and make sure it doesn't ratchet down easily. That may have confounded your setting. If it's loose, tighten it. If not, you might try replacing the front sight. Lastly, check the aperature itself and see if the hole is obviously off-center.

Ty

 

[RustyHammer]

No harm, no foul.

 

[AZ Jeff]

MANY M-1 gas cylinders tend to be loose on the barrel. This is due to the great number of times the cylinder has been removed by grunts during the innumerable cleanings these rifles went through.

The real issue here is not the AXIAL variation in gas cylinder location, but the RADIAL variation. I have grabbed many a DCM/CMP rifle as delivered, and have seen the gas cylinder rotate slightly relative to the barrel. This has the net effect of having your front sight have built-in variable windage. It sure has some weird effects on your accuracy!!

The solution, for even those of us who are not creating match-conditioned M-1's, is as follows:

Pein one or more of the gas cylinder slots in the barrel GENTLY on both sides of the spline grooves. Use a small hammer and a flat punch. The idea is to narrow the splines JUST ENOUGH to create a LIGHT interference fit with the gas cylinder.

Then, slide the gas cylinder on to the barrel, and use a rubber mallet or a block of wood to lightly tap the cylinder on until the gas cylinder lock can be threaded onto the barrel. Final gas cylinder location is done by using the gas cylinder lock to draw the cylinder into position, centering the rectangular cut in the gas cylinder over the port in the barrel.

When tightening the gas cylinder plug into the gas cylinder, restrain the gas cylinder, NOT the barrel, during the torquing, to avoid damaging the splines.

Do NOT remove the gas cylinder unless absolutely necessary once it's peined tight onto the splines, as the removal loosens the cylinder again.

 

[plevniak]

Once again good information

Thanks for all the comments.

I'll have an update for everyone on the 28th after the M1 clinic.

 

[Freedomv]

Sir when adjusting your rifle's sights it is important to know at what range you will be shooting the rifle and what sight picture you will use.
When I build an M-1 for "match" shooting and for using a "six" c'clock hold, and Knowing that the shortest range that I will be shooting is 200 yards. I like to have about 6 clicks for elevation. I'll machine the front sight to the correct hieght to accomplish this. for obvious reasons a new sight has to be tall enough to start with to machine anything off of it. I also taper the front sight on each side narrower towards the front and slope the sight down in the front to make for a much clearer and precise sight picture.
If you anticipate shooting 100 yards you may not be able to use the rifle with the same sight picture as there may not be sufficant adjustment to lower the rear sight.
As one man said earlier--- Make sure the rear sight is tight, but still operational with your fingers for adjustment during a match. ie don't use pliers.
I don't remember where I got the information, but the ideal fit for the gas cylinder take up nut should be to rotate it on the barrel and find one that will tighten on the barrel at the 7 o'clock position and then back it up to the 6 o'clock position and the install and tighen the lock nut. Thats the way I have done all of the match rifles that I have built and they work just fine. The idea is not to bind the gas cylinder to the forend stock and to obtain the best accuracey I ream the gas cylinder for clearance on the barrel. There are many more things to do with accurizing an M-1 than can possibly be covered here. and as I haven't built a match rifle in years its hard to remember everything that was done untill you start in building one again.
Also there are others who may have differant or conflicting ways or ideas of doing these things.
That's my two cents worth.
Vern

 

[plevniak]

Range report

Well the M1 Clinic didn't have the time to cover my situation but I did get to talk to some guys during the day.

The end result is, that the perceived movement I felt was negligible. After shooting my 5 sighters for the match the rifle, I noticed that the movement I had felt before was nearly gone. After the 50 round match, It feels nice and tight. Apparently, it needed some fouling to lock up the cylinder. I still had to set a 26 click (from zero) elevation to hit center with a 6 O'clock hold.

In response to the above post about the desired ranges I'd like to shoot, 100 is the minimum and I think 400 will be the maximum for my eyes with iron sights. I regularly shoot 200yd matches which is what I had.

Also, I had planned on changing to a "center" instead of a 6 O'clock hold for 100yds too.

I was told that 0.008 inches is what I need to shave off the front sight to adjust the rear sight by 1 MOA (1 click).

In summary, the problem with the gas cylinder is solved of its own accord. Now, how should I go about shaving off the front sight. Dremel? What kind of bit? Is this a job for a gunsmith or can a guy with a dremel do a good job?

What Would be the Ideal # of clicks for a 100 yd center hold and, with the same front sight adjustment, what would the 200 yard 6 O'clock hold be?

 

[Freedomv]

To remove metal from the front sight obtain a small file and blunt the edges so that it will not cut into the sight protection ears and file away.
Start by filing from the muzzle towards the action. I like to file the front lower than the back so as to get a clearer sight picture. If you have a caliper or micrometer to take readings (measurements) with it would be helpful. Be sure to hold the sight solidly in a vise or other fixture ( not between your knees) and use a black magic marker to color the sight after each inspection so you can tell where you are filing. It would be a good idea to practice on so scrap steel before you start.
If you have trouble with gauling load the file with chaulk and it will help illiminate the problam.
Good luck! Let us know how it turns out.
Vern