Garand gas cylinder play

lazarus · May 30, 2018

http://thecmp.org/training-tech/armorers-corner/gas-cylinder/

So it seems like some is normal and at least a tiny amount of front to back is necessary to keep heat expansion from throwing off point of aim.

Mine seems to have maybe 1mm or front to back play (gas lock is tight about the 1 o’clock position and then has to be rotated back just over half a turn to insert the gas plug).

It also seems to have maybe 1 degree of rotation side to side (maybe not that much, maybe half a degree) and the gas cylinder is easy to take on and off.

Reading the above article it seems like that is all pretty standard. However it would be better for less play for better accurizing.

Thoughts/suggestions? Get some extra locks and see if one times better to make it tighter? Peen the splines for a tighter fit? I am a little more concerned about the rotational play. It seems like it is enough to throw point of impact off a couple of inches.

Only took me 3 times to get the reassembly correct

PS or is my better bet just getting it to the range and seeing how it shoots?

Art3 · May 30, 2018

I peened mine and then just figured on leaving it alone while cleaning... :shrug:

(that sounds...out of contextish).

There are videos. It didn't take much, and it seemed to me like there was plenty of spline to repeat the operation if necessary. Mine was tight...until I took it apart

Blacksmith101 · May 31, 2018

Take it to the range and have someone who is a known good Garand shooter shoot it and see what it does. What ammunition are you planning to use?

Orlando · May 31, 2018

gas cylinder should have no rotational or back and forth movement

Clifjr · May 31, 2018

I think you are talking about the front hand guard? Most have movement as all of mine do. But my first Garand when I received it from the CMP had very little if any and when I first shot it, the front hand guard developed a hair line crack. Cause was the lower band was twisted and from what I read it was common for match type rifles. I got a flat lower band, fixed the guard and haven’t had a problem since.

John from MD · May 31, 2018

Art3 said:
I peened mine and then just figured on leaving it alone while cleaning...

(that sounds...out of contextish).

There are videos. It didn't take much, and it seemed to me like there was plenty of spline to repeat the operation if necessary. Mine was tight...until I took it apart

+! Peening is an accepted method of eliminating the slop.

lazarus · May 31, 2018

Okay, thanks! The front hand guard is pretty tight as it is new CMP walnut. There is a gap between the gas block and hand guard which my reading says is needed, but the whole gas block can slide back and forth about a millimeter and can rotate maybe half that.

So it sounds like peen it and leave the gas block in place for cleaning if at all possible.

Thanks! I guess I need to get a 1/4” flat punch. I swear I’ve done tons of auto work and built half a house mostly by myself and I literally own no flat punches. I’ve got scads of concave and convex punches, but no flat punches :-(

for ammo I’ve got 140rnds PPU 150gr Garand ammo and 12 clips. I hope like heck I don’t need to run through all that to get it zeroed. Also hoping to get it to the range this Sunday. My carbine will stay home. It is it’s own range trip as I need to replace the front sight. It came to me with a scope rail instead of sight in the rear. I replaced with late war correct sight (it is an early carbine though) and it is way huh at 100yds. Like 8 inches high. So I got a NOS sight when I got new springs for the Garand and carbine (the new spring is about half an inch longer than the old one). So time to pull the old one, install the new one and take a file and a bucket of ammo to the range.

Orlando · May 31, 2018

There is no reason to remove the gas cylinder for cleaning. Basically its self cleaning. I do a complete tear down and clean once a rear and that's if I'm shooting 1000 rds
All you need to do for normal cleaning is clean the bore, wipe down the outside or all metal with oily rag

lazarus · May 31, 2018

Peening did the trick! I haven’t tapped the gas block fully in to place yet, but seems good and firm and even on all of the splines.

I am certainly going to try to leave the gas block in place once I reinstall it, which is why it hasn’t gone back on yet. I am rubbing the stock with BLO and I’d like to get at least the first two coats on with the front handguard off the rifle.

I am hoping to get it to the range Sunday morning, so no more than 2 or maybe 3 coats total before it’ll need to be reassembled and dry. I am torn on BLO and truoil. I love me some truoil, but I know that isn’t correct for a Garand and I’d need to buff it a lot to give it a good matte finish if I truoil the stock. Fortunately I can truoil it at any point even if I’ve BLO’d the living daylights out of it. So for now, it gets 2 or 3 costs of BLO and reassembled. Once back together I’ll give it another couple to few coats once my first range session is done, with the front handguard in place, but action out of the stock.

dist1646 · May 31, 2018

There are 3 slots so, peen only the right side or the left side of each slot, never peen both sides. You may want to consider taking it to Charlie Maloney for a complete inspection, worth every penny.

charliesarts@comcast.net

www.charliemaloney.com

John from MD · May 31, 2018

+1 on Charley. He is one of the best M1 gunsmiths out there.

lazarus · May 31, 2018

dist1646 said:
There are 3 slots so, peen only the right side or the left side of each slot, never peen both sides. You may want to consider taking it to Charlie Maloney for a complete inspection, worth every penny.

charliesarts@comcast.net

www.charliemaloney.com

Opps, a little late now. All of the videos and written guides said to do both evenly.

dist1646 · May 31, 2018

lazarus said:
Opps, a little late now. All of the videos and written guides said to do both evenly.

Oops! I was told the proper way to do it by my buddy Ray Parkinson of AMU #1.
Yep, the same guy who built JFK's M1 Garand.

Peening both sides is not as stable as just doing one side and will eventually work loose again. Peening one side lasts longer.
Since it is already done, just go with it, that's all you can do for now. I would definitely take it to Charlie for a full inspection.

lazarus · May 31, 2018

Well, it had some light, but visible peening already. So someone had tightened up a gas block at some point in the barrel’s life. I guess if it works loose i’ll try peening just the one side.

Orlando · Jun 1, 2018

I have peened both sides and never had one loosen up. As long as you are shooting and not unnecessarily removing the gas cylinder it will stay tight

dist1646 · Jun 2, 2018

Orlando said:
I have peened both sides and never had one loosen up. As long as you are shooting and not unnecessarily removing the gas cylinder it will stay tight

I have seen some that stay reasonably tight and some that have come loose. Groups become more like shotgun patterns when they work loose. I agree with unnecessarily removing the gas cylinder, even if only one side has been peened, as it will accelerate the deterioration of fit.
As stated earlier, I would have Charlie Maloney inspect the rifle. He is local and his fee is very reasonable. He will tell you what, if anything, needs to be replaced or needs to be watched so that you can plan ahead for any potential needs.

lazarus · Jun 2, 2018

dist1646 said:
I have seen some that stay reasonably tight and some that have come loose. Groups become more like shotgun patterns when they work loose. I agree with unnecessarily removing the gas cylinder, even if only one side has been peened, as it will accelerate the deterioration of fit.
As stated earlier, I would have Charlie Maloney inspect the rifle. He is local and his fee is very reasonable. He will tell you what, if anything, needs to be replaced or needs to be watched so that you can plan ahead for any potential needs.

After a first shoot, maybe? I used a guide on what to inspect and took my calipers to everything. Everything seems to be within specs. The recoil spring was marginal/short (19.5”) and I replaced that with a new one from fulton armory (20.3”). Only thing I had no way to measure was throat and muzzle erosion, but I am willing to trust CMPs measurements that came with it.

Doco Overboard · Jun 2, 2018

Careful fitting and observing the gc as it is led up to the splines on install before it is driven on by peening the bottom outside spline-ways at the corners can help help center the gas port and move the rear of the cylinder up and against the bottom of the barrel to tighten it up.
Have a lock on hand that indexes properly and the angle of the punch and the degree of hit will influence how the rear ring of the cylinder winds up for straight once the cylinder is finally installed.
I like to avoid not supporting the gas cylinder when tightening the plug or hefting the weight of the rifle by grasping the assembled components once it's done. Barrel metal is soft on the end and moves easily.
Your front sight picture could be improved too by its face being square when you look at it.

Orlando · Jun 2, 2018

Do not use a gas lock that stops to far from 6 Oclock and force it to time. I do not know why but it will make accuracy go south, I know this from experience

Doco Overboard · Jun 2, 2018

I think maybe its because of the threads between the barrel, contact surface of the lock not being square and the 45 degree barrel shoulder. The lock could have high spots that creates stress on the barrel when it's too tight before 5:30. It makes a kink of sorts. Heating and cooling of the barrel changes harmonics between shots.
My shooting is not consistent enough to tell, I just like playing with the rifles and certainly do not posses enough parts to continually swap them around to do any sort of consecutive concrete evaluation.

Garand gas cylinder play

The #1 community for Gun Owners of the Northeast

Member Benefits:

Ultimate Member

Eqinsu Ocha

Grumpy Old Man

Active Member

Active Member

American Patriot

Ultimate Member

Active Member

Ultimate Member

Ultimate Member

American Patriot

Ultimate Member

Ultimate Member

Ultimate Member

Active Member

Ultimate Member

Ultimate Member

Ultimate Member

Active Member

Ultimate Member

Users who are viewing this thread

Log in

Forum statistics