View Full Version : glock 20 10mm problems

February 7, 2011, 04:59 PM
i have a glock 20 10mm 3rd gen that jams with full power loads it ejects the spent shell and sometimes the slide closes on a empty chamber the mag dont feed but more often the new round gets turned up the slide hits the middle of it and jams it acts like the slide is out running the mag spring it does it stock and it does it with a 22# and 24# wolff spring and guide rod and a wolff extra power mag spring i tried 4 new mags same result it works fine with normal velocity ammo but i got a 10mm for power if i cant shoot full power i dont need it i have a .40 glock already ive had several glocks and this is my first gun to jam its driving me crazy does anyone have any ideas?

February 7, 2011, 05:06 PM
What normal velocity ammo are you talking about? What brand? And what is the grains is the bullets? I don't have a Glock, but have been shooting 10MM for a bit.

Mtn Biker
February 7, 2011, 06:05 PM
Make sure you are using a firm grip and not "riding" the recoil back. You"re probably not but just throwing a suggestion out for thought.


February 7, 2011, 06:20 PM
Sounds like you've tried quite a few things. I have a G20 also and had problems but it ended up being the magazine follower. Replaced it and problem solved. Sounds like that's not your problem though. I would have to echo the previous poster. I would go to the range again and make sure you have a high tight grip. If you do, and I'm guessing you do, I would suggest calling Glock. I don't know. :confused:

February 7, 2011, 06:24 PM
My 20 has always operated flawlessly with whatever ammo and with stock parts it came with years ago. Dunno what with all that you've already tried. I would call Glock. I've heard their customer service is second to none. Good luck.

February 7, 2011, 06:34 PM
Gosh, how 'bout a bit of punctuation, your post was a bear, and I don't mean the coach, to read.

Are your mag bodies clean? A dirty mag body could be slowing the rise of a ctg for feeding. Also, are you using factory mags?

Glock's are mostly notorious for being reliable. I'm curious about your "full power ammo". Are you talking reloads or boutique ammo?

Corbon mentions a heavy recoil spring for their heavy ammo, to combat premature slide unlock. They mention wide velocity spreads. Whether this would effect feeding I could not say.

Typically, most auto pistol probs are linked to magazine, maintenance and ammo.

Mine runs fine.

February 7, 2011, 06:41 PM

February 7, 2011, 09:33 PM
The ammo im having problems with. Double tap 230 grain hard cast 1120 fps and swampfox 200 grain xtp 1240 fps.Ive shot CCI 200 grain tmj,Winchester 175 grain st,Double tap 180 ce hp and they all ran fine.Maby i got a lemon. The gun is only a few months old,I figured i would see if anyone here had any ideas before i sent the gun back to glock.

February 7, 2011, 09:38 PM
And its not my grip i have a very firm grip.And i even tried to limp wrist it with the 200 grain CCI. I could not make it jam,Thanks for the advice tho.

February 8, 2011, 12:38 AM
Please take a little time to make your future posts more readable. I find it pretty disrespectful on your part that you would post something that torturous to read instead of taking the extra few seconds it would require, at most, to include punctuation.

February 8, 2011, 01:02 AM
maybe try a lower poundage on the recoil spring, 24 lbs seems high even for the 10mm maybe try 20lbs and maybe try a different mag.....and if your worried about slide impacting frame with a lower poundage spring then buy a recoil buffer

my 2 cents...maybe worth it maybe not

February 8, 2011, 01:15 AM
Comparing alabama's 1st post to his later posts, I think he got the message about punctuation.:rolleyes:

Good jod alabama, your later posts are just fine.;)

February 8, 2011, 01:25 AM
From what your saying, I believe it to be the ammo. Typical trouble shooting of a gun doing the same problems, you have already done. Some guns just don't like certain types of ammo. The two certain types of ammo that you are experincing problems with are, in themselves, pushing the balistic boundaries of the 10mm. In other words, they are very hot and the bullets are big. One more thing that you can do is, take a caliper and measure the over all length of the ammo you having problems with, and compare that length to the ammo that is functioning perfect, see if that gives you any clues. If you don't think Glocks can jam, try feeding a 155 Grn 40sw bullet in a model 23.
Remember that semi-autos are an engineering marvel, and several things have to be perfect in timing to make everything run reliable. Glocks themselves are neat because of the advent of a simple, reliable, and lose tolrent gun. However, even they have their limations. you can make any firearm jam by creating a certain enviroment. Just be content on knowing your weapons limitations, so you don't jam in a critical incident.

February 8, 2011, 06:26 AM
I do think the other posters have a point, if your pistol doesn't like the 230 grain load, then I wouldn't sweat it, as this bullet is a bit too heavy for the caliber. The 180 grain and 200 grain bullets already provide plenty of penetration.

I usually shoot the 10mm with a 180 grain bullet at 1200 fps. I haven't seen a .40 S&W that (safely) comes close to that. The best I've heard of of are ultra expensive Double Tap .40 S&W 180 grain at about 1100 fps. My reloads are about $10 per 50 still beating out that top .40 S&W by 10%.

The only suggestion I have is to try a few different recoil springs. Perhaps the 230 grain bullet isn't as hot as we think? It could be eating up a lot of case capacity with the heavy bullet.

February 8, 2011, 10:10 AM
This is only a guess, and but I've shot a S&W 1006 for many years using everything from hot Corbon 135 gr. to the 200 gr. CCI's you mentioned. I've always run either a 16# or 18# Wolff spring. Forget the factory ballistic numbers, especially with the hard cast loads. Even in a 5" gun, you will be very lucky to come within 200 fps of some of those numbers. Still, the 10mm is a mighty handfull with full bore 155 or 180 gr. loads.

Having stated those differences, I'm guessing you need to weaken those springs quite a bit. That is, if you are happy at heart with the shape and angle of your ramp and forcing cone, particularly near the top. Those long slugs will run nose-first into the roof of the chamber when forced too quickly, and it may require additional polishing around the cone orifice. Taking that into consideration, the wire coil diameter is also much thicker on the heavier springs, meaning the compression distance will be reduced accordingly.

A 5" slide must be allowed to move freely over the entire load length of the spring, both to operate the cocking mechanism at the rear and to strip the new round from the follower on the return trip. If the travel distance or compression force is too extreme, there is also very likely not enough time to allow the next round to feed up, then be stripped and fed into the chamber because of the binding forces of the compressed spring trying to rap the slide forward too quickly.

If you are feeding Hornady 180's or 200's reliably with the stock springs, they should certainly be reduced to feed what I would guess to be even weaker, heavier rounds. I would literally lighten everything up, and try to visualize what angle those rounds look like they take into the chamber mouth upon entry. If your ramp is still at the appropriate height and the magazine followers are free and level, then you should be good to go. Timing means everything in semi autos. When in doubt, ask for help. There is no shortage of opinions on Glocks or anything else on the www.;)


Carne Frio
February 8, 2011, 12:00 PM
Sorry that your having a problem with your Glock M20.
Since my Glocks have not yet malfunctioned I'm not
able to offer much advice. What did Glock say to you
after you contacted them ?

February 8, 2011, 07:38 PM
I have not yet contacted glock .Im going to try and find some different ammo to try maby a 180 xtp at around 1250 fps and see if it works better.My main concern is reliability but i would like to have atleast 600 # of energy. I only carry the gun when hunting or camping i use the 40 for everything else.I might be going to Idaho for work soon,if i do then the 20 is what i would like to take. Thanks for all the advice does anyone have any on ammo for my purpose ?

February 8, 2011, 07:44 PM
Does it have the issue with other mags?
Have you tried a new mag?
Do you store ammo in your magazines for long periods of time?
I would say it is more than likely a mag issue.

February 8, 2011, 08:20 PM
You may have a weak recoil spring(guide rod spring), weak magazine springs, or gunk built up around the extractor. It's also possible that your magazines simply need to be disassembled and cleaned thoroughly.

Here's a video showing how to detail strip and clean the internals of the slide, but DON'T get oil inside the internals, it will quickly collect gunk and cause the gun to malfunction. I personally use Hoppe's Elite Cleaner to detail strip clean.

Even though your malfunctions are happening with all four magazines, the cause could still be weak magazine springs because if you've been using all four for the same period of time, they'd all become weak at relatively the same time. When these malfunctions occur do the magazines have the Glock-brand springs in them or the Wolff extra power? It could be that the change in velocity of the slide along with stronger mag springs could be keeping the slide from picking up the next round easily enough.

The problem may not even be the gun, the springs, your grip, etc, it may be simply the shape of the bullets in those Double Tap loads. I haven't heard of feeding problems in a G20 with Double Tap 200gr WFNGC, but the 230gr may be pushing it. If the problem is the shape of the bullets, a test you can do is to use the stock recoil spring with the cartridges in question and chamber a round from the magazine by pulling the slide all of the way back and releasing it forward. If it fails to chamber when doing this, either you have a weak spring somewhere, dirty extractor, or the shape of the bullet just isn't right for your gun. If the gun consistently succeeds in chambering a round this way, your problem likely lies in the combination of spring rate and power factor of the load you're using.

February 8, 2011, 08:53 PM
Yes they are all factory glock 15 round mags and 3 of them had never been used. The only reason i put the wolff extra power spring in 2 of them was to see if it would help but it didnt,it does kind of seem like a mag problem but after trying 2 with extra power springs and 2 factory mags it just doesnt make since.I dont know if it matters or not but all 4 mags have the number 1 stamped on the body and the number 2 stamped on the follower.The gun is very clean i took it apart cleaned it and looked for damaged parts every thing looks good to me.Oh and i havent had it jam on the last 5 rounds in the mag it seems to work till i put 6 or more in.

February 8, 2011, 09:03 PM
This may not be a problem with the major brand name loads and it may not be a problem with your other Glocks, but maybe it's only happening with the Double Tap 10mm loads, it's worth trying anyway. When loading your magazines use the magazine loader that came with the gun. When you push the top round down with the magazine loader, it pushes down on the rear of the round. Try using your finger to push down on the front of the round while the magazine loader is pushing on the rear of the round, this way the round doesn't tilt and move backward/forward as it's being pushed down. Now with the top round held down by the magazine loader, partially push the next one into the magazine, lift the magazine loader, then push it the rest of the way in.

It's never been a problem for me with my .40 Glocks, but I've noticed there is a decent amount of extra space front to back in the magazines and it may be causing problems for you with the Double Tap loads.

The point here being that all of the rounds are as far rearward in the magazine as they can be, up against the rear of the magazine.

February 8, 2011, 10:12 PM
Voyager that was good advice,i loaded my mags and cycled the action by hand like you said and one of my mags failed every time. I even put the factory spring back in and it still jammed i think its the follower.The other 3 worked fine by hand. I guess its possible that i kept trying the same mag over and over when shooting it with all the mags and springs i had laying around,so i will try what little ammo i have left of double tap and swampfox and see if maby it was the 1 mag the whole time, if it was then i will feel really stupid because i thought i tried all of them.I will let yall know thanks again.

February 9, 2011, 04:45 AM
Kay guys I got this off buffalobore's website

Full power 10mm ammo has always generated enough recoil and pressure to require a pretty stiff recoil spring in your handgun - this of course depends on several variables such as your slide weight, etc. When the cartridge fires, it generates enough pressure/recoil to prematurely open your breech face in some guns. When this happens, the opening breech face has an effect on the burn rate of the powder. This can result in some fairly high extreme spreads in velocity. If you are experiencing extreme velocity spreads of more than 50 fps, simply install a stiffer recoil spring. For example, I have an original Colt Delta Elite. This gun with the factory spring runs extreme spreads of about 35fps with both of these 10mm loads. I am happy with 35 fps, so I leave the Delta Elite as is. I also have a custom built Para Ordinance with a Nowlin barrel. It runs extreme spreads of about 70 fps with its original recoil spring. When I install a spring that is 4 lbs stiffer, the extreme spread drops to about 35 fps. The new Glock model 20 comes with a recoil spring that allows the breech face to open too soon and my new Glock model 20 will get extreme spreads of about 100fps with the factory spring installed. When I go to a stiffer recoil spring, the extreme spreads drop to about 50 fps in my new Glock model 20. Of course none of this will be an issue in a revolver. None of this will be an issue in real life either, as these high extreme spreads don't hurt accuracy or function. However, I mention this because if you are like me and want things to be as correct as possible, I have outlined the problem and the solution. The industry fixed all these problems initially, by watering down the 10mm ammo over the last several years. The watered down 10mm ammo does not generate the pressure/recoil to open the breech face early. If you want the full powered 10mm ammo we make, you simply need to tweak your pistol. Or just realize that you are getting some fairly high extreme spreads and ignore it or live with it. It's not hurting any thing in reality

February 9, 2011, 09:29 PM
Ok im pretty sure it was my mag i shot both types of ammo i was having jams with.It worked fine with new mag i didnt have enough ammo to test it good though.I will order more and test it better.I feel confident it will work now

February 9, 2011, 09:36 PM
+1 for me...:D

February 9, 2011, 09:45 PM
If I have a failure with a weapon and I think there is any way it could be the magazine. I put a small mark on that magazine. Any mag with more than one mark I try to figure out whats going on with it. Just thought it may help you in the future.