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thebrow 10-05-2006 07:16 AM

Gas system maintenance on M1 Carbine?
I guess I am showing how much I know about the M1 Carbine but this is my first one. I bought an Inland that was built in '42. I have replaced every spring with Wolff Springs but still probably get 1-2 stove pipes or failure to return completely to battery. Can anyone comment on what they think might be happening and any solutions recommended? The only thing I can think of would be the gas system being adjusted improperly (if you can adjust them) or very dirty. Is there a way to clean out the gas port? Other than that it has been cleaned very well as far as I can tell. Stripped the bold and replaced all the springs there as well.

Any info you can offer would be much appreciated.


TommyGunn 10-05-2006 07:32 AM

You can't adjust the gas system. In fact unless you REALLY HAVE to clean it out the best thing to do to it is nothing. It isn't hard to tinker with if you have the tool to take off the collar but some people bugger the threads when replacing it, so that's why it's best not to do it unnecessarily.
You're problem isn't likely there, anyway. Check the extractor and ejector.
Sooner or later maybe a true carbine Guru will chime in with exactly what your problem is.

thebrow 10-05-2006 09:37 AM

Can anyone give me an idea on where to purchase extractors and ejectors? Also I need a quality bolt takedown tool. Bought one from Fulton Armory and it broke on me the first time I used it. I can still use it but not properly.

Audie 10-05-2006 11:16 AM

You can check the gas system for dirt by just turning the barrel/recvr assembly through the vertical and seeing if the piston moves in and out freely by gravity alone. If not, then just soak it in hoppes for a while and blow some compressed air to dislodge any dirt. the piston also sticks out about 1/4 inch or so.

the only problem you could have with the piston if it isn't gunked up is that someone screwed it in too far. I wouldn't mess with least it should be the last thing you try to fix.

Make sure you are not using an extra strenght recoil spring.

sounds to me, that your bolt needs to be cleaned. Get a bolt tool and learn to take it apart and clean it. If your extractor is frozen up, it could prevent the bolt going into battery. If you don't clean it, you will eventually break the extractor.

Take the bolt out and with a punch, make sure the ejector is moving in and out freely. then with a small screwdriver, place it under the extrator and push on it, it should move freely.

If it doesn't, it needs cleaning. If you don't want to take it apart, soak it in some hoppes and then some CLP, that should free up the parts.

Audie 10-05-2006 11:19 AM

Chestnut ridge supply
US Armory
bill ricca

do a yahoo search for websites.

btw, I cannot imagine how you could break it....make sure you are using it correctly. good luck.

just reread your post, you did take the bolt apart...make sure you got the plunger in right! and check that the extractor moves freely with a screw driver.

thebrow 10-05-2006 11:59 AM

One of the sides of the split broke very easily. Not even sure how it happened. I figured there must me a problem with the metal on this particular unit or the ones sold by Fulton are cheap. This doesn't go with what I know of Fulton since they are usually a top notch supplier.

I can still use it but not how it was intended.

Thanks for the information on suppliers. I may just need to get a new extractor and ejector. They do move freely and the bolt has been cleaned and lubed but the result was the same.


Quagmire 10-05-2006 12:42 PM

The pawls on the bolt tools are very easy to break. The slightest pressure with the bolt improperly aligned in the tool is enough to do it. You cannot force the pawl into position by tightening the screw when there is stiff resistance. Both GI and commercial manufacture tools are this way.

Buy another tool (you can't just buy the pawls) and be gentler next time.

dfariswheel 10-05-2006 04:17 PM

Here's the "usual suspects" on failures like this:

Change ammo and magazine.
Often it's nothing more than your specific rifle just doesn't "like" the ammo, or the magazine is defective.

Change the recoil spring for a USGI SPEC spring.
NO "extra power" springs.
The Carbine was designed to work with a specific weight of spring. Any changes may cause stoppages.

Check the extractor and spring, and ejector and spring.
Check for chips, cracks, wear, bad springs.
Again, GI-spec springs.
Check both extractor and ejector for free and full movement.

Check the bolt face for problems.
As above, the bolt tool is FRAGILE, misuse it and it'll break.
The "forked" end is for use when disassembling an early type of extractor plunger, and to position the "stepped" late-style extractor during reassembly.
USE THE CORRECT END, and guide the blade into the extractor plunger properly so it doesn't break.

Clean/check the chamber.
Look for fouling build-up, rings, pitting, corrosion, etc. Scrub it out with a .45 caliber pistol brush.

Check the gas piston for free movement.
The piston should move freely in and out about 1/4" inch.
Keep the gas system DRY. NEVER allow lube, solvent, or anything else to enter it. Clean the carbine with the sights down on the bench to prevent solvent and lube from running into the cylinder.
The Carbine gas system was "self-cleaning" with USGI-spec ammo. Commercial ammo may not run as clean.

If you MUST disassemble the gas system, get either a USGI manual, OR a copy of Jerry Kuhnhausen's book, "The US Gas Operated Carbines: A Shop Manual".
These show how to disassemble the system WITHOUT ruining it.
Before attempting disassembly, buy a piston nut wrench, and a NEW USGI gas piston and piston nut.

Replace the old piston and nut during maintenance of the system.

Check the op rod for binding, both in and out of the stock. Both with and without the recoil spring.

GREASE the Carbine.
Apply a good heat and water resistant grease to the bolt, bolt lugs, cam area of the op rod, op rod grooves on the barrel, op rod lugs on the rod "box", front face of the hammer, receiver op rod grooves, inside rear receiver where bolt rides.

Last, remember that Carbines have been in God knows how many hands and God Only knows what they might have done to them.
Look for any signs of tampering or alterations, or non-GI or GOOD GI parts.

Audie 10-05-2006 05:09 PM

I agree and disagree with some of the above. Cleaning the gas piston with a solvent like hoppe's semi auto that leaves no residue as it drys works well. I agree not to oil it, but it can be cleaned.

magazines are rarely associated with ejection problems..they cause feed failures as does a worn mag catch.

If the bolt is working well, the extractor face may be chipped off or broken. I doubt it is the ejector.

Replace the recoil spring too, and make sure the bolt is back together properly. A plunger in backwards would bind the extractor.

Breaking a bolt tool is a bad sign that things are frozen up...but your problem is still there... :?: ....maybe it is the spring.

checking the slide for binding is a good point, that could be the problem. Put the gun together without the recoil spring and guide and make sure the slide travels smoothly with no binding whatsoever. That's a good call DFW.

jimb16 10-05-2006 07:41 PM

One more thing to try that the other guys haven't mentioned. It is unusual, but could be the problem; a bad mag catch.... Try shooting while holding the bottom of the magazine forward. If this stops the problem, replace the mag catch. Sometimes a bad catch will allow the front of the mag to hang too low and can cause this problem. It isn't common, but it is possible.

Bolo-7 10-06-2006 04:40 AM

As a few of you guys might know I have bought a few carbines over the years. Many, many times they are sold because they have a problem. What I have found after too dirty to work right is:
Number one is a broken extractor.
Number two is a extractor plunger, turned wrong, or cross ways about to come out.
Number three a cloged gas port. After removing the gas piston and nut, run a 0.070" drill bit carefully by hand. Start smaller and work your way up to 0.070". If you get a 0.065 to go that may be enough. I have removed lead, brass, packed burnt power, and one time old drill burrs.
Of course, one time I broke off the drill bit and had to shoot it out. That worked so I put another bit in it to clean it out and broke that one in it to. And that broken bit did not shoot out. And to my amasement, the carbine still worked.

Inland44 10-06-2006 05:40 AM

'I agree and disagree with some of the above. Cleaning the gas piston with a solvent like hoppe's semi auto that leaves no residue as it drys works well.'

Me too. Periodic use of dry-cleaning solvent in the gas piston will prevent this build-up. I also use special gun oil or solvent oil in mine, draining it out the barrel with the muzzle down. You just can't use any oil that will gum or harden. When the carbine manuals were written, synthetic and other non-gumming oils were not available to the troops, so they specified to keep fluids out of the gas system. The best stuff I know of to clean one without disassembly is 'Kreen' by Kano Labs. It's an engine treatment that dissolves hard carbon, and it works. In fact, since it's a rainy day, I think I'll treat mine and see if I get any black gunk out. 'Kreen' will generally free a frozen piston and restore the function of the gas system.

Audie 10-06-2006 12:15 PM

Good advice. that piston should move in and out freely just by gravity when tilting the barrel up and down. If you put a little maintenance there, the piston will give no troubles.

The extractor is a common problem area with the carbine. Order a few...nice to have a few in the parts box.

Bolo-7 10-06-2006 01:16 PM

"that piston should move in and out freely just by gravity when tilting the barrel up and down."
I would say ok, maybe. But many pistons takes a tap, tap on the side of the gas housing to get it started moving, ok. But as long as a light pull with pliers will move it, it will work just fine. Remember, 40,000 psi will make it work as long as the port is clean.
What should move freely is the slide and bolt without the spring and guide and trigger housing. First tilt up the barrel 45 degrees and back down 45 degrees and the slide and bolt should work smoothly. Also the slide arm should stay parallel to the receiver during the complete travel distance. The distance between the arm and the receiver should stay the same. If not, the barrel is not indexed correctly.
Maybe this is too much information?

Audie 10-06-2006 04:31 PM

Mine does...but it has been to the gunsmith and he took it apart and re staked it in place when he was done. I also clean it as above. :wink:

dfariswheel 10-06-2006 04:56 PM

The reason not to allow ANYTHING into the gas system is, there's no solvent or lube I know of that won't carbonize in the system.

The gas coming down the gas port is so super-heated it's plasma.
When the plasma hits whatever the liquid is, it instantly burns it to a tar-like sticky substance.

The Carbine gas system was intended to be run DRY, and as long as it was, and was used with GI-spec ammo, it was self-cleaning.

Most gas system problems I saw were caused by using non-GI spec ammo, or putting foreign substances in the gas system.

jimb16 10-07-2006 06:06 PM

That's why it is recommended that a carbine be cleaned upside-down. That way no oil or cleaning solution goes down through the gas port into the chamber of the gas system.

Eisenmetzger 10-08-2006 03:59 AM

There's a discussion about Wolff springs at the Marlin Owners forum.

Jim H

ChairborneRanger 10-08-2006 04:19 AM


Originally Posted by dfariswheel
The gas coming down the gas port is so super-heated it's plasma.

Check your physics, I think you'll find that it's still a gas.

Inland44 10-08-2006 07:57 AM

And gas systems are not self-cleaning. Any gas-operated weapon will eventually fail to cycle if the gas system is not cleaned. Sounds good in theory but in practice carbon still forms, with or without oil present. Has no one ever seen a gas port cleaning tool in the AK-47 cleaning kit? It has been my experience that certain oils do not carbonize in the gas system and can liquify the firing residues that do form, so cleaning consists of just wiping with a soft cloth and re-treating. No gas system of mine ever needs scraping, drilling or other harsh treatment. This includes an AR-15 with it's very dirty and trouble-prone 'direct impingement' gas system, dumping firing residues right into the bolt carrier/bolt. This is the main weakness of the system and is why any gas piston system is inherently better. BTW, gas piston uppers are now available for the AR. The M1 Carbine's weakness is potential clogging of the gas transfer port and piston, and the possibility of rendering the gun useless in the attempt to remove and re-install the gas piston in the field. Although this weakness was not a major problem while the carbine was in service, it's become a problem now because he carbine, like any other military weapon, was not designed to be shot for 60 years without a major overhaul. Firing residues from foreign and hand-loaded ammunition and lead bullets has eventually blocked many carbine gas systems, requiring the gas piston to be pulled for manual cleaning of the gas port and piston chamber. As long as this is done by a competent person, there should be no problem, but many barrels have been ruined by cross-threading, over-tightening and failure to stake.

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