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GI Inland Barrel with Loose Gas Cylinder |
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jakebev 
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 Topic: GI Inland Barrel with Loose Gas CylinderPosted: Jul 16 2019 at 11:02am |
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  I posted elsewhere on this forum that I noticed my swaged gas cylinder is loose on my Inland M1 Carbine. I fired 10 rounds through it without considering that this may be an issue, and they all cycled fine. Of course, the question is, will this develop into a greater problem with further shooting? And is there any way to correct it without shipping my gun off for months and spending hundreds of dollars to have it fixed? I'm moving out of the country in September, so I don't really have time to ship the gun off if it's not going to be back fairly quickly. And of course, this carbine was worth what I bought it for, but not much more, so any large expenditure turns a good deal into a bad deal. It is a rough, but original Inland that has not been rearsenaled with an adjustable sight, flip safety, etc. I've tried to illustrate in the pictures the amount of movement--about a 1/16th or less of rotational play--and no longitudinal play along the axis of the barrel. Anyone have experience with this or know what to do? Thanks Jake
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floydthecat
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Posted: Jul 16 2019 at 11:33am |
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I think you have answered your own question. Getting that repaired may cost more than you want to invest. The gas system naturally vents what it doesn’t need. I’d say that if it is sealed tight enough to cycle, just shoot it. I don’t think you’re going to damage anything.
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blackfish
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Posted: Jul 16 2019 at 11:59am |
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I would be a bit more careful. Not everyone has nine lives. Carbine stocks have been known to explode from catastrophic "venting" of gases in ways not envisioned by the original design, e.g. http://forums.thecmp.org/showthread.php?t=90616 |
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W5USMC
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Posted: Jul 16 2019 at 12:05pm |
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Understood that sinking more money into it may not be the best option, and if it works fine now sure you can shoot it and it may very well be ok, but as I mentioned in a post on your other thread, a loose gas cylinder can lead to problems if gas starts to leak between the cylinder and barrel.
The below is from Kuhnhausen's shop manual: "A looser than .0005" interference fit (i.e. a looser press fit) can permit gas leakage or venting between the barrel and gas cylinder even after the cylinder is swaged. This condition will, sooner or later, expand and crack a swaged-on type gas cylinder. Cracked gas cylinders are not repairable." |
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Wayne
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floydthecat
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Posted: Jul 16 2019 at 4:42pm |
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My thoughts were that as long as the piston is not stuck and vent gases can escape in the normal manner, the gun would shoot as long as enough gas-pressure got to the piston cavity. I certainly would not be one to guarantee it’s safety. Nobody can ever make that guarantee prior to any trigger-pull.
I think it’s a gun that needs to be fixed with either a barrel change or a cylinder replacement. It’s a shame it’s original. Maybe selling it to someone and making the issue aware to the buyer is an option. Like me for instance😁.
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New2brass
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Dan Pinto, Photo Editor Joined: Nov 29 2015 Location: CT Status: Offline Points: 4660 |
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Posted: Jul 16 2019 at 6:32pm |
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i would be interested in seeing the swage on the cylinder, you pics cut it off to the left
to the right on this pic  |
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jackp1028
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Posted: Jul 16 2019 at 7:50pm |
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Inland prototypes and early production barrels (Type 2A per Riesch) were secured with a pin and the gas cylinder could be removed, supposedly for cleaning. This suggests that the radial looseness itself is not a potential cause of failure. However, any axial movement could be a problem given the force with which the piston is driven. Perhaps a repair can be effected by duplicating the pin arrangement of the early prototype. See page 47 of "U.S. M1 Carbines, Wartime Production" by Craig Riesch (7th Edition) for an example.
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JackP
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jackp1028
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Posted: Jul 16 2019 at 8:54pm |
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@Blackfish, I had a Universal gas cylinder separate when the weld failed. The pressure wave caused the hand guard to blow off. Fortunately the blast went mostly upward and I wasn't hurt. Surprisingly the gas cylinder itself didn't damage anything.
 
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JackP
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jakebev
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Posted: Jul 17 2019 at 10:33am |
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New2brass: Here is a better picture of the swaging on the cylinder.
jackp1028: "Inland prototypes and early production barrels (Type 2A per Riesch) were secured with a pin and the gas cylinder could be removed, supposedly for cleaning. This suggests that the radial looseness itself is not a potential cause of failure. However, any axial movement could be a problem given the force with which the piston is driven. Perhaps a repair can be effected by duplicating the pin arrangement of the early prototype. See page 47 of "U.S. M1 Carbines, Wartime Production" by Craig Riesch (7th Edition) for an example." I like this idea, but I do not have a copy of that book (or any carbine books for that matter.) Can you post a picture of what you are talking about? Also, a similar idea would be to have a gunsmith pin and weld the gas block in place like an AR15 flash-hider (someone may have already suggested this). Probably cheap and quick too. Thoughts?  |
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W5USMC
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Posted: Jul 17 2019 at 10:56am |
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Or was there a potential for failure, which is the reason they dropped the pinned gas cylinder and went to the swaged. Just my opinion but I believe that the only fix for a loose gas cylinder is barrel replacement. |
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Wayne
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floydthecat
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Posted: Jul 17 2019 at 12:55pm |
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I haven’t read that much concerning re-swaging one and don’t really know if it could be done, or trusted. I’d agree with the barrel change and to one with an integral cylinder. A welding job seems like a possibility. If it’s not bleeding-off enough gas to malfunction now, a good silver-solder fix may solve the problem and allow the original barrel to stay with the gun. I just don’t think it’s going to blow-up from the leak as long as the port is not obstructed and the piston is free.
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W5USMC
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Posted: Jul 17 2019 at 1:14pm |
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And you may be right, I have seen a lot of really good welding and brazing jobs in my day that ended up with better than new repairs, I wish forum member manteo97 would chime in with his thoughts. |
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Wayne
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floydthecat
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Posted: Jul 17 2019 at 4:19pm |
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Manteo97 has been my go-to guy for things I could ship to him. Too bad we can’t send him a barrel.
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jakebev
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Posted: Jul 17 2019 at 4:37pm |
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Glad to see a weld job is perhaps a possibility. I agree, it would be good to hear someone who has more welding experience chime in.
The barrel replacement idea is obviously another solution. But I'd like to avoid that if at all possible. I'd probably just sell it rather than pile $300-400 into a new barrel and labor.
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jackp1028
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Posted: Jul 17 2019 at 10:14pm |
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Jake, below is a picture from the book I'm quoting. Either pinning, silver soldering, brazing or welding would probably be okay as long as the port is open and the piston operates. However, anything that requires heat may cause changes to the barrel or gas cylinder hardness or may introduce warp. That's why I like the pinning. As you noted, pinning is used to secure the gas block on the AR. Also, even though the gas cylinder seems loose, it is still retained axially on both ends, at the rear by the shoulder of the larger barrel diameter and at the front by the existing swage into the groove cut into the barrel. Even if properly swaged, it is only really tight at the swage itself. The tolerances of the parts allows as much as .006" clearance between the gas cylinder and barrel along the un-swaged length. according to the original Army Ordnance drawings. It's not going anywhere. I don't think you need to replace the barrel if it's okay otherwise.
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JackP
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floydthecat
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Posted: Jul 18 2019 at 5:17am |
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Gas cylinders on guns like the Garand and M14 actually slide off after removing a retainer and most of them are cast. Gas blocks on Mini 14’s are held in place by screws and as mentioned, AR’s are pinned. This barrel may have left the factory this way? When two pieces of metal are squeezed together they must be over-squeezed to account for rebound. Surely they had to limit this when swaging the cylinder to the barrel to prevent barrel damage and it was only squeezed enough to hold it in place. Gunsmiths “sweat” things together all the time on barrels, such as sights and muzzle-devices. After I consider all that’s been posted here, I think a spot-weld or a pin would fix this right-up.
Maybe Jack’s Universal failed due to piston action against the slide with that force acting against a poor weld? Edited by floydthecat - Jul 18 2019 at 5:47am |
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New2brass
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Dan Pinto, Photo Editor Joined: Nov 29 2015 Location: CT Status: Offline Points: 4660 |
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Posted: Jul 18 2019 at 3:20pm |
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how about re-swagging the cylinder?
If it is just a slight rotational issue with no forward motion maybe just a few stake marks on the edge where it meets the barrel?
I think that the port was drilled with the cylinder in place. If it rotated or slid forward I would think the action would start to get sluggish or fail to move the piston. I do not see how there could be catastrophic failure with this. Discussion?
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jackp1028
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Posted: Jul 18 2019 at 4:07pm |
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@Dan, I would be concerned that staking might aggravate the looseness. I agree that there needs to be a way of limiting the rotational movement so the gas port in the barrel does not misalign with the gas port in the gas cylinder. If it's allowed to rotate 1/16", that will nearly block the .070" port. Also, any movement will have the effect of "scrubbing" the space between the barrel and gas cylinder whenever the gun is fired causing wear and increasing the looseness. If the cylinder is not allowed to move, the small gap between the cylinder and barrel will eventually be filled with carbon. The rest of the section in Kuhnhausen's book that Wayne is quoting goes on to say that two problems with brazing or welding is "zone barrel softening, warpage and bore distortion...and zone embrittlement." It is suggested that this could lead to gas the cylinder cracking. That is why I'm in favor of pinning.
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JackP
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jakebev
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Posted: Jul 18 2019 at 4:09pm |
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It seems we can generally agree there isn't a safety issue, but that we need to "stop the bleeding" and make sure the gas cylinder doesn't "unswage" more.
Kitchen Gunsmith Ideas: Braze around the swaged edge of the gas cylinder (higher difficulty) Drill and tap a hole through the cylinder and into the barrel, insert a small plug screw to hold it there (medium to low difficulty) Do a small pin and weld job on the gas cylinder (like an AR-15 flash hider) (higher difficulty) Somehow try to replicate the pinned on block like in jackp's post (similar to how an ar block is pinned on) (higher difficulty?) Take a punch and try to stake it around the swaged edge (as New2brass suggests) (low difficulty) My brother is going to help me out a little on this project as well. He has a little more ability in this area. Any votes? haha
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jakebev
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Posted: Jul 18 2019 at 4:18pm |
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Jackp1028: Does the pinning job depicted in that picture bite up into the barrel a little bit? Kind of like the rear hand guard pin on a garand?
I forgot to add another option--the ultimate kitchen gunsmith idea: JB Weld Steel Stick
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floydthecat wrote: