Gas Lock Timing Question

[cuppednlocked]

With all the discussion of gas lock timing i am wondering if I can squeeze a little more accuracy out of my JCG rifle.

My gas lock stops at "7 o'clock". I'm backing it down to 6 and tightening the gas cylinder/plug TIGHT. The gas cylinder is brought away from the front handguard.

I don't have a stockpile of gas locks and don't really feel like investing in a bunch for the few rifles I actually own. The rifle shoots pretty well if I do my part. How necessary is it to time the gas lock at 5:30?

Am I chasing my shadow?

[timshufflin]

I'd like to hear some anecdotal evidence as to this working.

[Orlando]

That mod by itself and with surplus ammo I seriously dont think you will see any difference
That mod plus everything else you can do to a Garand you will see a differnce in accuracy
I really think the best thing you can do to increase a Garand accuracy is put it in a new well fitting commercial stock and use handloads or Match ammo.
Gus Fisher told me the main thing it does is take the torque/stress off the barrel threads when you have a lock that properly times as it puts the lock against the angled seat on the barrel

[timshufflin]

Orlando, if the "mod" really works, there should be some proof of it working by just doing this mod shouldn't there?

[Orlando]

One thing you dont want to do is use a lock that stops hand tight at 4:30 and torque it on down.
I did this and accuracy went to crap, as soon as I used a lock that stopped at 5:30 or more accuracy came back

[Orlando]

Orlando, if the "mod" really works, there should be some proof of it working by just doing this mod shouldn't there?

Again all it does it take stress of the barrel threads and keeps gas cylinder tight longer.
Here is a quote from Gus on the subject


"For NM accuracy, we don’t want a GC going loose during a match as the front sight will be in a different place each time and cause loss of accuracy when the GC is not tight on the barrel.

I do not know who first came up with choosing locks so they would tighten down with some torque to the 6 o’clock position. I think that information has been lost to history. With this method, the lock actually tightens against the angled front surface of the barrel that is called the “Gas Cylinder Seat. By the lock tightening against the barrel, that helps keep the GC from coming loose. I am not a mechanical engineer, so I can’t explain it properly in those terms, but tightening the lock against that shoulder actually takes stress off the barrel threads and key ways and is why the GC’s stay tighter for longer periods with this method.

Personally, I fit ALL M1 Garand GC locks this way as it is good for ALL Garands. I was informed even standard Infantry Armorers did this in the 50’s, after the method was developed and if they had enough locks to do it. Of course, it was the standard method used by NM Armorers. However, it took too much time for manufacturers or the Arsenals to do it with mass quantities of Garands and that’s why they never made it a mandatory maintenance requirement

[cuppednlocked]

The rifle currently sits in a nice, tight HRA USGI stock.

With the lock timing past 6 and not resting on the "gas cylinder seat" it's just going to loosen the peened gas cylinder splines? To preserve the peening I should find another lock?

[Orlando]

Or dont woory about it ,when and if gas cylinder loosens you can peen them again

[canes7]

Unless your cranking down on it, like in Orlando's scenario, I don't see how it's going to make too much difference at 100 or 200 yards. I don't give two shits about lock timing anymore.

[Roadkingtrax]

When you shoot at the top 5% of the game...I could see how all little nuances make a difference.

The rest of the 95%,...if you worry about gaslock timing as it pertains to accuracy, you aren't as good a shooter as you might think. :)

Man size targets....all this "squeeze accuracy out of a rifle",...squeezes the fun out. :(

[Orlando]

I used to try to try all these little mods on the Garand and found that with a Standard Garand it really doesnt make any difference

IMO
Biggest factors o faccuracy in this order:
Ammo
Careful fitting of commercial stock
Trigger job

[timshufflin]

I used to try to try all these little mods on the Garand and found that with a Standard Garand it really doesnt make any difference

IMO
Biggest factors o faccuracy in this order:
Ammo
Careful fitting of commercial stock
Trigger job

I'd add a tight muzzle. To me, as long as everything else is operational, everything else falls into the "C" list.

[canes7]

Don't forget the shooter.

[Roadkingtrax]

Don't forget the shooter.

It's all about how you hold your mouth...

This may also be useful in other professions,...also seen on the CMP forum. :)

[cuppednlocked]

if you worry about gaslock timing as it pertains to accuracy, you aren't as good a shooter as you might think. :)

I'm not sure if that's a dig, but I would say that if the rifle is performing to it's max potential the only variable is the shooter. The only excuse is the nut behind the trigger. I had a question and it was answered.


Man size targets....all this "squeeze accuracy out of a rifle",...squeezes the fun out. :(

I'm certainly not as serious a shooter as Canes or Orlando, and I am the definition of inconsistent offhand. When I get to shoot a match I like to shoot a small group (given what I feel are the "spirit" of the games: issued ammo/no mods other than the careful fitting clause). I don't reload and won't for a long time if ever. It's factory or surplus for me. Granted I'm shooting 100/200 yd matches, but this is the level at which I choose to compete.

I try to have all my firearms as accurate as possible, especially the ones I hunt with. I may not be able to use them to their potential but I sure as hell try!

[Roadkingtrax]

Not a dig at all,...I am just saying that I think it would be the last thing. Ref. Orlando's list:

IMO Biggest factors o faccuracy in this order:
Ammo
Careful fitting of commercial stock
Trigger job

I, too, am in your group of non-reloaders...and I can make any rifle shoot bad. I've come to the realization that I have two choices, I can try to fix every nuance and glitch in the symphony of the M1...or shoot more to find my own position and see what a straight up rifle can do. I think the rules get skirted in the games matches, but my shooting beats me everytime.

No offense meant by anything.

[Orlando]

[QUOTE=cuppednlocked;30793]
I'm certainly not as serious a shooter as Canes or Orlando, and I am the definition of inconsistent offhand. [QUOTE]



Trust me I'm not a serious shooter, sure theer are many guys here that could clean my
clock. When I didnt have work I did spend atleast one day a week at the range but all I did was compete against myself. With my back/herniated disks and eyesight not what it used to be I am starting to shoot more glassed rifles off the bench.
I do find that I'm real rusty now since I dont have time to shoot near as much. Time at the range really makes a difference

[Jim Oliver]

This may not mean anything to anybody but here goes, anyway------
I was able to spend some time with Gerald "Hook" Boutin a few years ago and learned lots more than I could comprehend about accuracy for JCG match rifles.

Per Mr. Boutin, the fit of the gas lock is very important to the overall accuracy, but won't fix a worn muzzle, or loose stock, etc. Hook had a large bucket of GLs to select from when fitting gas cylinders; he would sort through 'til lhe found one that pulled up hand tight at ~5:30, then wrench it on very slightly past 6:00 then back off to 6:00 for final fit.

He mentioned that the front handguard fit and the fit of the ring on the gas cylinder were important, as well. Most know about the handguard fit, but the gas cylinder ring should ideally not bear on the bbl. or be a very light contact.

Hook showed me how to modify (probably not JCG legal) the gas lock to allow the proper 5:30 fit; he removed a tiny bit of the seat side of the GL to allow a GL that pulls up too early to then turn a bit more to get to the 5:30 position. The problem is making certain that the metal removed leaves the seat surface flat and square with the bore. Otherwise, uneven pressure is applied to the tapered seat on the bbl.

So.....I bought a "few" gas locks and replaced three or four on my rifles (all with near new MW & TE numbers). I also found that, if you have enough rifles, you can swap parts and maybe find some locks that fit one rifle much better than on the other.

The proof is in the shooting----on my three rifles that I consider JCG match guns, all in CMP walnut stocks, with very tight lock-up, I am able to get five shot sandbag groups of 1.5 to 2 inches with my 155 AMax loads.

The one rifle that Tim rebarreled (Krieger GI contour) with CMP mount and Luppy 4x pistol scope, I have fired several 1 to 1.5 inch 5 shot groups.

A friend recently brought his Benneli (spelling) .30-06 auto loader with 3.5-10 scope out to zero---The Garands were more accurate than the Benneli :)

Jim

[Punch The Clown]

My personal limiting factor seems to be lighting. A brightly lit target and I'm golden. Overcast or getting near dusk and I can't see.

[cuppednlocked]

RKT,

No worries my BT brother!

[precision32]

I read the idea that some how having the GCL tight against the shoulder of the barrel removes the stress from the barrel threads. I have to ask; HOW????

It's the screw threads that force the GCL against the barrel shoulder.

[Punch The Clown]

The threads on the barrel are very soft. The play in the threads causes them to get hammered when firing, which will eventually wear them out. If the gas lock/thread play is eliminated no more hammering. A tightly fitted gas cylinder also reduces the stress on the threads.

[precision32]

How many rifles have you seen with the barrel treads worn out from GC movement?

[jak]

How many rifles have you seen with the barrel treads worn out from GC movement?

I had a S/A field grade with worn barrel threads. With the gas cylinder lock and gas cylinder lock screw tight, I could slightly move the gas cylinder and gas lock front and rear. I tried several gas cylinder locks with no change. I slightly flatten all the thread on the barrel and installed a NOS gas lock. The gas cylinder didn't move after that.

[Punch The Clown]

How many rifles have you seen with the barrel treads worn out from GC movement?

I've seen a lot of barrels with worn threads, although I admit I've never done any kind of scientific analysis as to why. Here is an old post from Jouster by Gus Fisher. He claims to have seen thread wear that he blames on gas locks.

http://www.jouster.com/forums/showthread.php?9464-Fitting-a-Replacement-M-1-Gas-Lock/page2

[precision32]

"Even though I know of no hard and fast evidence or studies on fitting GC locks;"

Nothing is going to change the recoil impulse. The energy is going to work on the threads no matter what you do.

Jak, how do you prove that the wear you see is from the threads not being tight? How do you tell the wear from normal tolerance of the treads?

[Punch The Clown]

e=mv^2

Sort of the way a hammer works.

[precision32]

I know what you're saying. But if the threads can resist E, than they will not be damaged. I have a 100 stone anvil (225#) that you can bounce a 3# sledge off of all day with out damage. ;)

[Punch The Clown]

I don't know, it's just another thing that we can busy ourselves with. The fact that the barrel and the gas lock have mating tapers built into them makes it look like they were designed to -mate. I'm not sure of the thread spec on the gas lock and barrel but most feel way looser than a 3a/3b fit. On the other hand try screwing a FAL barrel into a receiver. It's almost an interference fit. Now add on a loose fitting gas cylinder and you not only have frictional wear on all the surfaces but gases escaping which will erode the surfaces. If you manage to get a snug fit on the gas lock taper it will keep the hot gases away from the barrel threads. Messing about with guns is a hobby, so why not take a little extra time and go for that perfect fit and finish.
Shuff goes a little bit extra on these things. He machines his gas pads with an extra couple of thou of interference. You need a dead blow hammer to get the gas cylinder on but they ain't moving and they ain't leaking.

I draw the line at bolt lapping though.

[jak]

Jak, how do you prove that the wear you see is from the threads not being tight? How do you tell the wear from normal tolerance of the treads?

Normal thread tolerance allow for a very slight movement of the gas lock on the barrel threads which is normal for any type of nut and bolt arrangement. On my rifle I was talking about there was front to rear movement that you can not only feel but see. Just screwing and unscrewing the gas lock on to the barrel a thousand times would not cause the threads to wear out. The barrel threads were damaged by the threads of an improperly tightened gas lock slamming back and forth into the barrel threads every time the rifle was fired. All my other garands show no front to rear movement of the gas cylinder/gas lock when properly tightened down. That includes several WWII garands with original barrels that obviously had several thousand rounds fired through them.

[timshufflin]

"Even though I know of no hard and fast evidence or studies on fitting GC locks;"

Nothing is going to change the recoil impulse. The energy is going to work on the threads no matter what you do.

Jak, how do you prove that the wear you see is from the threads not being tight? How do you tell the wear from normal tolerance of the treads?

I have seen worn barrel threads but have no way to prove how it happens nor do I care to. How many barrels have I seen that have threads with forward and aft movement? Not many at all, maybe 2% or so.

This being said, that is my 2% observation, the theory that a tight lock will help thread wear does make sense and here's why.

Energy = weight x Velocity squared. When you have a tight lock, that cannot allow the lock to move, you eliminate the velocity which forces the lock forward against the threads. You still have the weight portion of the formula but without the speed squared, the wear should be greatly reduced be theory.

[Phil McGrath]

Here is my .02 for what its worth, if you don't subscribe to the theory that anything the moves on the M1 should do so freely and return to its at rest position in the same manner. Anything that shouldn't move doesn't, makes a more accurate/repetable rifle than a timed GSL isn't for you. It was explained to me that If there is a gap between the barrel shoulder and the GCL the G/C now has some wiggle room under recoil and from the barrels harmonics, the only thing countering this is the barrel splines. The barrel splines will come loose again if only peened from a combination of shooting harmonics/recoil and G/C removal for cleanings. A GCL thats snug @ 6 allows for less wiggle room and offers more support for the peened splines. The peened splines stay tighter over a longer period of time, recoil there is nothing we can do to prevent that other than never shoot the rifle, The barrels harmonics the same but we can try to get the G/C and the barrel to dance closer to the same rate this also helps to take some pressure off the peened splines with less movement. I don't think timed GSL makes any M1 more accurate, it helps maintain its accuracy longevity over a longer duration.


The thread issue about recoil/harmonics wearing them out I don't know were that came from, I can see the threads wearing out from repeted removal from cleanings or trapped grit/crud from the field, but not from actual firing of the rifle. Like you guys I don't have a pile of GCL to try on my rifles. Niether was I willing to buy or drag my barreled action to every gun show in search of one that did. I was lucky that I had a friend that sent a pile of them for me too try out and hopfully one would work. I was lucky again one timed up and is on my rifle now, my future plans are to complete the NM mods and shoot it XTC.