M1 Carbine - Short cycling?


June 6, 2016, 12:00 PM
I have been wrestling with an intermittent M1 Carbine problem. This is a mixmaster commercial Universal drilled on left side for a scope. Problem: cartridges will feed, fire and eject normally when the bolt is operated by hand. After 2 or 3 rounds (various magazine types) the bolt stops 1/8" short of battery. Pushing the bolt forward by hand chambers the round, which then fires normally. Reason: the extractor does not snap over the rim.

Original obvious problem: Gas piston and gas piston nut were missing. Owner does not know the history of the rifle. It now has a new piston and lock nut, although I can't determine the style or if it can be used in this particular rifle. Gas port is clean, piston chamber clean. New action spring. Cleaned out the bolt, ejector and extractor. The only suspicious thing is the power of that extractor spring. I know next to nothing about M1 carbines, but that extractor spring seems very stiff to me - the bolt is clean and lubed and (as above) will always chamber a round if the bolt is pulled back and released manually.

Is this a type of short stroke problem? If the bolt is not thrown all the way back, the action spring won't have enough power to chamber the next round. Incorrect piston, weak ammo? Should I open up the gas port a little?

None of the M1 carbine ammo I have seen has the velocity listed on the box. Is that typical?


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June 6, 2016, 01:20 PM
First and unfortunately for you the Carbine is a Universal, they did not function reliably even when new. I do not remember the piston/ op rod relationship to one another but i am sure GI Carbine parts will for the most not fit your rifle. It is obvious from your description that gas and probably an extractor are causing the problem, i would suggest a competent gunsmith inspect and fire the weapon. Once you get it running you will siill have -----a Universal! Sorry

June 6, 2016, 01:34 PM
Years ago I had a Universal Carbine and despite it not being 'GI'...it worked fine...so that in and of itself isn't necessarily what's wrong with yours not locking up after chambering. If the extractor spring seems too stiff to you, it very well might be. No harm in pulling it out for a look-see just in case there's mung in there blocking the free movement. Maybe have a fresh spring on hand and go ahead and swap it out just to see what difference...if any..it makes. If the round gets that close to locking, it does seem logical that the extractor might be blocking it.

June 6, 2016, 01:54 PM
Always start with the simple things first. First, verify if your carbine is indeed short stroking. Using a mag that is known to lock the bolt back, place one round in the mag and use it to load the rifle and fire it. If it locks back, the rifle isn't short stroking.

From the description of your malfunction, my be is that the action spring is failing. I would recommend you replace the action spring. Cheap insurance with a used rifle, even if it isn't the primary source of your problems

June 6, 2016, 03:00 PM
The recoil spring was replaced according to the OP also the extractor spring is normally very strong...what he has is just a guess without seeing it. I would zero in on the gas system as it has been changed and the original parts are not there for comparison. Universal used a couple of different operating rods including ( if the brain bag remembers correctly) one utilizing two recoil springs. The OP should seek the assistance of someone knowledgeable on Carbines that can visually inspect what the OP has to work with.
My apologies to Universal owners who have/had Carbines that work properly. Unfortunately many did not and they have a generally bad name in the Carbine world. I received two Universals in trades through the years, I collected GI Carbines and simply used them as trading fodder, if i remember correctly both operated just fine. Today any Carbine GI or otherwise seem to bring a premium, having a Universal I can see why the OP would want it to work.

June 6, 2016, 08:12 PM
I worked on a GI carbine a long time ago for a similar problem, what I found was a fair amount of shaved brass packed tightly in the notch (for lack of a better term) that the extractor rests in when the bolt is closed, until I cleaned the brass out, the bolt would not go completely into battery, it was causing the extractor to jamb on the rim instead of sliding over it. Just something else to check.


June 7, 2016, 01:02 PM
The recoil spring was replaced according to the OP also the extractor spring is normally very strong...what he has is just a guess without seeing it

The symptoms described point to a weak action spring even though the spring has been replaced. It is possible the replacement spring isn't up to spec and I would be looking into that. There is no profit in looking at other sources of trouble until the spotting is positively eliminated as the source of the malfunction.

True, we are not looking at the rifle first hand. But that does not change how to troubleshoot a gas operated, air cooled rifle. The very first thing the rifle should be checked for is short stroking. Until that is confirmed or eliminated, any speculation is useless.

Second, the spring must be positively eliminated as a source of the malfunction. Until those two things are accomplished, everything else would be tail chasing.

Cleaning out the extractor as suggested by Claymore (as well as any other spots that may have collected any dirt & debris) is an excellent idea and should be done before beginning any troubleshooting

Carl N. Brown
June 7, 2016, 09:05 PM
How much energy the slide receives from the short stroke pistol may be an issue. My 1943 IBM seems to have been set up correct; I suspect it would be a nightmare to adjust (requires a special piston nut wrench and the nut has to be staked in position with a punch once properly adjusted).

And I almost hate to say it, but I suspect a Universal might have its own set of problems due to Universal carbines not always being strict GI in design over the years of production. Universal started when lotsa GI parts were available; as they dried up or got more expensive, Universal started making parts of their own design.

June 7, 2016, 09:26 PM
Universal M1 Carbine Production History (http://maxicon.com/guns/universal_m1/universal_m1_carbine_production.htm) is a pretty good read on the Universal flavors over the production of the rifle. Some will argue the early production guns were better. Personally I never owned one but bought and sold many and shot several. While directed at the actual GI versions a very good shop manual on the rifle is The U.S. .30 Caliber Carbines A Shop Manual by: Jerry Kuhnhausen. (http://www.amazon.com/U-S-Caliber-Operated-Service-Rifles/dp/B0006F5XOW)

Short stroking can have any one of a number of causes:
Defective Ammunition
Barrel gas port restricted or partially plugged.
Port holes offset (some commercial models)
Gas Piston under size diameter.
Gas piston worn or out of round.
Gas piston sticking from carbon or dirt in cylinder.
Gas cylinder over sized or worn.
Gas cylinder leaks, around barrel. (cracks around barrel commercial versions)
NOTE: The commercial versions did have a good number of gas problems. Since your rifle came missing gas system parts I would be looking long and hard at the gas system.

There are literally a dozen more possibles and that is just for short stroking. Bolt failing to close and lock also has a dozen possibles. My suggestion would be find a competent smith familiar with the M1 Carbine rifles. A good smith is hard to find. You can chase a problem like this with and endless string of parts and never get the rifle to function correctly.


Steel Horse Rider
June 7, 2016, 10:29 PM
If you take it to a smith be aware that the Universal inner workings are not GI. Mine is from the late 1960's (I believe) and has two springs instead of a single. The gas piston is about a half inch diameter and pretty short on the stroke. I would start there by cleaning the port and piston first, then the slide components. I know the doubters here will laugh but I have not had any more problems with my Universal than with my Saginaw Gear Works real deal. Both are a blast to shoot.

June 8, 2016, 12:21 PM
Thank you all for the helpful comments. I'm glad to know that the Universal models were not all that great - it figures. That's probably why the original owner got rid of it. You are right, an experienced M1 carbine smith would be able to spot incorrect parts and possibly get the thing to work.

As stated earlier, the action spring was replaced (no room for 2 springs) and the other springs in the Wolff kit - some of them are for other models. Yes, the new action spring is the right one, and stiffer than what came out. The clue for me is that rounds always chamber when the bolt is pulled back by hand. AND that stuck cartridges will chamber if the operating handle is bumped forward. Magazines feed. Bolt locks back - if you have the type of magazine that provides that feature.

I know this rifle is loved by many, and that it has a great history in battle. I just don't think I'm holding the real thing in my hands. Frankly I would rather try throwing a rock than using this thing to protect myself.

This rifle DID have the brass shaving problem described above. It is caused by a frozen extractor and ejector along with weak springs - basically a bad case of short stroking and lack of maintenance.

Interested if it is common practice for the M1 Carbine ammo box not to specify the velocity? Of course, I'm looking for the magic 2000 fps number. Weak ammo would be one possible cause of the problem. I think this particular rifle is going to be recycled very soon.

Thanks again,

June 8, 2016, 09:49 PM
Well, Universals did not go to war (they might have gone to Cuba, or to Laos/Cambodia/SE Asia--but were never issued)

If you find an ace gunpumber for M-1 Carbines, they may well be at sea with a Universal. They are not GI. They do not assemble like GI, they are not plumbed like GI. That's why you had extra springs from the Wolff Kit--Universals use different springs than GI. And with little rhyme or reason.

I bought a Universal as it was cheap. I found out why. It had only the one spring even though it was set up for two. The bolt had a push bitton for a bolt hold back--but the receiver had no cuts for the pin. I should have known better just from the perforated metal upper handguard (which hid how Bubba used a hatchet and dull butter knife to hack at a GI stock to make it fit the Universal.

Frankly, I'd try the original action spring back in it and see if the problem persists or gets worse. I'd also look for someone with stated experience with Universals.

loose noose
June 9, 2016, 11:14 AM
Wireman, I've got the Iver Johnson model, which I believe was later produced by Universal, mine will inter-change with all military (GI) issued parts, including springs etc. Note mine is also just the single return spring. I bought mine used, however, I have put well over a 1000 rounds thru it with out a hitch. I realized when I bought it, that it wasn't the real McCoy but it is a real blast to shoot. (pun intended).

June 10, 2016, 09:07 PM
The early Universal was interchangeable with the USGI Carbine.
It was in the later 1970's that Universal did a major redesign of their carbine and after that it was more of a carbine lookalike.

The later Universal had two recoil springs, a redesigned gas cylinder system and a op rod that was made from stamped steel, welded together.
You can easily ID one of these later Universal's by the cut out area in the op rod where the bolt cam surfaces are.
You can see the right hand bolt lug through the op rod.

It was these later Universal's that had a bad reputation, although not all were bad.

One common problem with all types of carbines both USGI and commercial is the use of extra-power recoil springs.
The carbine was engineered to use USGI spec ammo and a specific USGI weight recoil spring.
Many people install extra-power springs thinking it will help, when it often causes problems.
These extra power springs often cause problems like "short stroking" which can cause chambering issues.

The second issue is the ammo. Much of the current production ammo is not made to USGI specs and often gives problems.

My first move would be to install a new USGI spec recoil spring and try some different ammo.
Second, check for the op rod assembly rubbing on wood, or for wear or damage to the op rod "box" lugs and the grooves in the barrel the box rides in.

June 10, 2016, 09:56 PM
It sounds to me like it is not chambering. Change the extractor and it's spring

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