malfunctioned to dead last in a carbine match

I went to my first carbine match last night. I took my IJ mutt along for the ride. Some of you may remember my little adventure building this thing. After the build was done I had a good running plinker that was ready to go.

It's been to the range a few times and usually performed well. The failures to feed and failures to eject are history.

Last night, I decided to take it out to play with the others. There were twenty ARs, one AK, and my friend brought his Mini 14. Disturbingly enough, the guy with the AK asked what caliber I was shooting because it made big holes in the target. :ugh:

The first stage was set up to use 26 rounds. I ran my original IJ mag and one of the Korean mags. After round #6, I had a double feed. Clearing the jam meant pulling the mag and cycling the bolt. Two rounds were dropped in clearing the gun. Two shots later it was instant replay. Thinking it was the mag, I dropped it and inserted the Korean mag.
Four rounds later, I got another double feed. Two more rounds were dropped clearing the jam. That resulted in not only me being short of ammo to finish the stage but also the slowest time of ANY competitor in ANY of the four stages.

The RO running beside me stated it was a mag problem. I tend to agree.

For the second stage I took the three Korean mags. It was a 32 round stage and I carried 45 to be sure I'd complete it. This time I had two double feeds with two magazines. Again, it was the slowest time for the stage.

The third and fourth stages both had one double feed. I carried all four mags but only used two per stage.

I only have the one IJ mag and three Korean mags. All of them are 15 rounders. Until last night I had not experienced any mag related failures. The only thing I did differently was load the mags the night before
to minimize the amount of gear I had to carry.

Am I right to blame the mags? Things got better through the event but I've never had this problem before.

I understand that there are some really bad mags out there but the Korean pieces have a fairly nice reputation.

If it's something like the mag lips being spread or a related issue, are there measurements I can use to verify the dimensions?


The rifle is my Iver Johnson with a new Criterion barrel (properly head spaced) in a pot belly stock. The recoil spring, guide rod, extractor spring, gas piston, and gas nut are all new.
The range officers did comment about my shot placement. I only missed with two shots fired. Considering it was my first action match and the failures I had that is a bit of a consolation.
Next time I'll be sure to carry at least 4 mags on each stage so I can just drop 'em and go if there's a failure.

Information I got is the correct measurement of a carbine magazine is 1.5" from bottom of locking lug to top of magazine. Anything less indicates a worn or out of spec magazine that will not feed correctly.
If this is happening to several different magazines it could also be the magazine release is worn out or out of spec on your carbine. I have had both conditions occur with mine over the years.
I number each magazine also. It is easier to track if one is going bad.

HTH

It may be magazines, or it could be several other things: 1) Gas system problem causing short strokes. 2) Bad ejector/spring, 3) bad extractor spring. How far and to what clock position is the brass ejecting to, and how consistant or erratic is ejection.

By double feed I assume you mean a standard Type Three Malfunction - fired brass left in the chamber with the next round's nose pressing up against the base of the still chambered brass. That is a failure to extract, and the extractor had to somehow not be able to remove the fired brass from the chamber to leave it "in the way".

The most likely problems are: 1.) Worn or improper spec'd extractor and/or spring and plunger. This could also be due to the bolt being improperly machined if not GI. Try US GI parts. 2.) Rough or dirty chamber. First clean/brush throughly - then inspect with mirror for scratches, pitting, etc. Have it polished by a gunsmith, or do it yourself if you are sufficently skilled and have the right equipment. 3.) Dirty, corroded and/or out of spec ammo - reloads are always suspect, do all testing with new, US Major Brand Ball ammo, first. Reloads might need case trimming, foreign stuff may be out of spec.

I would do all testing of a malfunctioning carbine with only US GI new to excellent magazines and US Made, fresh major maker Ball ammo. Minimize the variables. Good luck and let us know how it goes. CC

Finally, none of the clone Carbines are likely to be as reliable as US GI. The IJ reciever may not locate the trigger group/magazine correctly if not in spec. With Ball, the GI guns are very reliable.

Those I knew put 18 rds max. In my experience, carbine magazines tend to fail in two ways: The rounds will move forward and bullet points tend to drag on the front of the mag body. Reloads that are too long are notorious for this. When you combine the collective drag of the points on the mag body, and add the drag of the follower as it reaches full bottom position (it tends to rock sideways or front to rear) and at times the first round will load and the next in line just stays where it is, or maybe the rear or front of the round will pitch up, causing malfunctions. When I was in a match I would never load more than the needs of the string. Magazines tend to feed fine when only partially filled. Recoil and movement of parts tends to smooth out the flow of the cartridges in this condition. Also, with a new barrel I would consider taking a dremel tool and polishing the feed ramps of the barrel.

Quote:

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Originally Posted by DaveHH

Those I knew put 18 rds max. In my experience, carbine magazines tend to fail in two ways:... Magazines tend to feed fine when only partially filled.... I would consider taking a dremel tool and polishing the feed ramps of the barrel.

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While not a match shooter, I have shot M1 Carbines for 25 years. I shot with a DCM club and we were required to qualify every year. My boys also qualified with M1 Carbines when they were in Jr. high. In all that time the only carbine magazine malfunctions I saw were related to old springs. New springs solved the problems. The problems that led to Vietnam era soldiers to only load 18 rounds into an M16 20 round mag in my experience do not relate to the 15 round M1 Carbine magazines.

I do heartily endorse polishing the feed ramp. Especially on refinished carbines, 5 minutes spent polishing it will increase the smoothness of feed. Obviously, if you are reloading for a carbine you have to get the length right..

I do appreciate the info so far.

I experienced lots of base over bolt failures when building this thing. There were failures to extract and failures to feed.
After installing and head spacing the new Criterion barrel, dropping in a new gas piston with nut, welding up and fitting the guides on the slide, and replacing all the springs with Fulton Armory stuff the failures went away.
I also cleaned up the receiver, trigger group, and bolt bits.
In short, it's a fresh build that functioned beautifully with the remaining IJ parts as well as with GI parts from my friend's Inland. Even the head space was on with his bolt.
The little guy has been 99% reliable since the rebuild. A couple failures have happened but they were a result of my reload development.

The failures I had during the match had a live round poking it's head into the chamber with the bolt trying to strip a round out of the magazine.
It was a double feed in my book. I don't know what the technical term might be.
The empties were going away nicely and function felt normal until the jam would hit.

The only thing I did differently was load the magazines the night before the match. The idea was to minimize the amount of stuff I had to carry. If I took two ammo boxes I would have needed to use the much larger case or leave the gun tools and cleaning kit at home.

Is it possible that the lips spread out on the magazine and rounds were popping out under recoil? The loads I was using are right down the middle of the charts with 100 gr bullets at 1950 fps. It was the most reliable load during my testing.

Gosh feets, this commercial carbine has been through SO MUCH tinkering, modifying, cutting etc it's hard to even venture a guess at this point,

Sometimes the aftermarket springs can actually cause problems, even in UGGI spec carbines, Maybe this is something to think about. Do you still have the original springs?
Didn't you cut the barrel skirt, or weld something?

Look out! It's a newbie with carbine problems!

You're using aftermarket Korean mags in a commercial carbine, correct? I'd go simple first and get a couple of good USGI magazines from one of the forum members before going into anything too complex and try them.

I recently sold a bunch of new USGI magazines to our member kikokat Military Surplus Collectors Forums (John) and he's selling them. John's a great guy and nice to deal with. I'd contact him and get a couple before doing much else.

~ Harlan

Thanks for the lead. I'll talk to him about some magazines.

I removed the barrel skirt on my lathe. The head space is good and the front sight is 1 degree off to the right. Trying to face the barrel to bump that one degree out of the sight is NOT worth the trouble.
I do have the original springs. I think they might have been part of the issues I was having early on in the build.

obviously they are different. I mention reloading because even factory loads leave very little room and even a slight bit too far on a reload can make them stop cold. The very blunt shape of the round doesn't help either. I'm seriously thinking about changing springs in my carbine mags as here in California we can't just buy more and a few are troublesome. I have been shooting carbines since Boy Scouts and that was in the mid 50s. I think that magazines are the weak link in the weapon, just my opinion.