Glock 20 Feeding Problems

[kamakiri]

Hi folks...

I'm trying to figure out a persistant problem with a Glock 20. It's been feeding rounds erratically, frequently failing to go completely into battery. This only seems to happen with hi-cap mags-- older ones with plus extensions and also both old and brand new, unmodified factory mags. Ten rounders run fine. There are no problems with spent brass ejecting.

The ammo is Rainier 180 gr. JHP sitting on 5.1 gr of Titegroup, loaded to a length of 1.250. It was running fine in the gun for a while (about a year) and then this problem gradually developed. Replacing the recoil spring with a new, captive guide rod spring seemed to help for a little while but then it cropped up again. It's inconsistant; sometimes a whole mag will run through fine, other times it will fail to feed on every shot. Again, there's no problem with 10 round mags.

I'm wondering if there might be some subtle difference in the way the two kinds of mags feed rounds, based on different spring pressure or whatever, that is interacting with something subtle about the load to create the malfunction. Load length is pretty consistant, but I'm wondering if it should be slightly shorter or longer, or if the crimp needs to be greater. Or is the problem with the gun itself? It hasn't had that many rounds through it, I think somewhere in the vicinity of 20,000 or less.

If anyone has experienced this problem and figured it out, or just has some good ideas, I'd be grateful to hear from them.

Elye A.

[Flexmoney]

Might need now mag springs too?

[eric nielsen]

1. How often do you completely disassemble the gun & clean it?

2. Do you lube the inside of the slide where it pushes on the disconnector?

3. Can you post photos of the tops of your problem mags?

[kamakiri]

Flex,

I don't think it's likely that the problem is the mag springs, insofar as it occurs equally with older mags/springs and brand new ones, unless it's somehow connected to the difference in tension between hi-cap springs and 10 round springs.

Eric,

This is actually my brother's gun, so I can't say for sure how recently it was completely cleaned, but I don't think it's too dirty. Lubing the slide/disconnector meeting point is something I haven't tried, maybe that will help. I don't have the technology to conveniently post mag photos; I have looked at them real closely and I can't find any obvious difference between the hi-caps and 10 rounders. There are about 8 different hi-caps that have been tried, all with feeding isssues, and half a dozen 10's that work fine.

Does anyone think the problem could be related to the crimp on the load? I know that the bullet, charge, length etc. have been consistent since the start (when the gun was working fine) but it's possible the crimp may have loosened up-- maybe the edge of the case is creating just enough drag somewhere, combined with hi-cap spring pressure, to cause the malfunction?

Thanks for the input,

Elye

[driver8M3]

Replacing the recoil spring with a new, captive guide rod spring seemed to help for a little while but then it cropped up again.

<{POST_SNAPBACK}>

i had a similar problem with a 34. turns out the recoil spring (ISMI 13 lb) was broken. the broken coils (2 or 3) wound themselves into the rest of the spring so that it wasnt very evident that something was wrong. i shipped the broken springs (i had also had another spring break previously) back to ISMI and they replaced them, though i never heard what the problem was.

in case it matters, my springs were on a captured tungsten rod, and they broke on the end farthest away from the muzzle.

[kamakiri]

Well, we tried a thorough disassembly and cleaning of the gun, with special attention to lubing the slide/disconnector contact points; we also slightly increased the crimp on the load. The gun ran fine for three hi-caps' worth of shooting, then returned to its old jamming ways.

We noticed that when the rounds were failing to feed, what happened was that the cycling slide seemed to be missing the rim of the case and catching on the edge of the extractor groove as it pushed the round to the feed ramp, resulting in the round being jammed at an angle with the nose of the bullet pressed against the top of the chamber.

We also checked the recoil spring carefully and there's definitely no breakage. In talking this over with my brother, he mentioned that the change from the old to the new captive spring didn't seem to have made much difference in fixing the problem back when it first occurred.

What to try next???

Does anyone think that this could be related to an after-marked extended mag release? It's been in the gun for a while, and the gun originally functioned fine with it (for a year or so), but we seem to be running out of possible problem sources...

[Yardbird]

Definitely try the old mag release again.

[fishnfst]

Double check all of your magsprings.. Sorry if this seems basic... Make sure the springs are all in the correct direction... Are there any burrs on your extractor or breechface that would cause the round to hang up... It sounds like if it works fine right after cleaning then starts to malf after a coup;le mags of ammo it could be something getting dirty. Hows the throat of the barrel? What pf are you running? Does it seem like the gun is shortcycling? I had a similar problem right before one of my frame rails delaminated. THe slide wasn't making a full rearward cycle. Could be a multitude of problems..... Have you measured the feedlips on all of your mags??? There is something that the 10 rounders have that are making them work that the rest of your mags don't have....

[Kevin Kline]

kamakiri,

Have you found what caused the problems yet?

[EricW]

You need new mag springs.

[kamakiri]

Kevin--

No, we haven't figured it out yet. One other thing we tried, just for the sheer hell of it (and because it helped a friend who was having a different sort of feeding problem with his Glock) was removing the slide stop, but that didn't help.

Everybody else--

I really don't think it's the mag springs. The gun is having the same problem with old high-caps with old springs and brand new high-caps with brand new springs, some of them modified with extensions and some of them exactly as they came from the factory. I just find it hard to believe that all eight or nine of these different magazines all suddenly have the same spring problem simultaneously. We've only shot a few hundred rounds through the 10-round mags, so maybe (given the erratic nature of this problem) those will ultimately starts screwing up too; I'm pretty sure at this point that something is wrong with the gun itself. But what???

[EricW]

My experience has been that ANY generation of mag coupled with an extended basepad results in FTF, especially on the last one or two rounds in the mag. If you're going to run extended basepads, longer/stronger springs are a must, plain and simple.

If the bullets are hitting the feedramp and stopping cold, this is the sure sign of a mag spring problem.

The cleanliness of the recoil spring assembly also has a lot to do with how much oompf the slide is driven forward with. You may need some oil or grease on it to slick things up. Normally, they're supposed to run dry, but it might help.

When all else fails, strip that sucker down to the bones and clean the bejeezus out of it. Get it squeaky clean, inspect it, then relube and reassemble.

[carinab]

Odd ball issue similar to yours hit me in the middle of the 96 world shoot. Turned out to be the magazine release. It was worn and so the worn, older mags sat lower than they should. I'd try the old catch and see if the same thing happens. Next I'd look at the malfing mags. Are the grooves where the mags lock into the catch okay? Sharp clean edges with no obvious wear? Just my .02....

[Chuck Anderson]

Carina's answer would be my first guess. Replace the mag catch and try again. This is not an uncommon problem. It may also be that the notches on the magazines are wearing at uneven rates. Is the mag catch that he put in the gun metal? If it is, get it the heck out. Metal mag catches destroy Glock mags.

Next best guess would be recoil spring/rates. Try switching out to a new stock Glock recoil spring assembly. Glock springs work pretty well but there's no way to really tell if your aftermarket spring is just shot out. I've had some last 30k and some last less than 1k. If the recoil spring isn't doing something to slow the slide down a bit, i.e. too weak, than the slide could be coming forward before the round has a chance to pop all the way up. The 10 rounders may be a bit different because they don't have as much weight to hoist and may be popping up more quickly. Have you tried the hi-caps with partial ammo loads? Say 3-4 rounds in the mag and see if it functions.

And put the slide stop lever back in the gun. It's not going to affect your problem. Try putting empty mags in the gun. Rack the slide. If it's not catching and holding open, there may be something else wrong as well.

[warrior23]

Put the gun back to stock form,and shoot factory ammo out of it to see if its still doing it.If its still malfuc then you know your reloads aren't the problem.Do you know anyone who has a G-20 that can fire off a few rounds with your mags?