Glock 20 Feed Problems

[Nick_C_S]

This is a long story so I’ll make every effort to keep it concise:

I bought my Glock 20 (SF, Gen 3) in California, in 2013. As most know, Ca has a 10-round mag capacity cap. I bought extra (10rd) mags – possessing eight total. I load my own and bought a fair amount of factory ammo. I bought a Lone Wolf barrel and a 20Lb tungsten guide rod/recoil spring. With all different combinations of barrels, springs, and ammo, the gun functioned near flawlessly – like a Glock.

In ’22, I moved to Idaho, where some residual freedom still exists. I quickly bought four 15rd mags for my G20. I didn’t get around to shooting my G20 with the new mags until last fall. I brought all four mags out, and two different types of ammo: Both 180gn, both my handloads. One was a Montana Gold JHP, using Power Pistol (fairly hot round), with an OAL of 1.255.” The other was an X-treme plated FPRN, using AA#5 (somewhat de-tuned round) and an OAL of 1.245.” I had the tungsten guide rod, and the Lone Wolf barrel in the gun. I always bring a clean, lubricated gun to the range.

I got lots of failures to feed. And a very specific failure: The tip of the bullet would lodge at the chamber breech at about the 10-o’clock position. All I had to do was pull the slide back about ¼ of an inch and the bullet would drop in. Back into battery, the gun would fire fine. This jam could occur at any time, but seemed to do more so on rounds two, four, and five – especially four. As the mag emptied, it would happen less, but still from time to time. There also seemed to be no co-relation to which mag – they all seemed to do it. Autumn was approaching and it gets cold here early (especially for a California pansy like me), so I let the issue rest until this year. I left all four mags fully loaded during the winter.

This year, I re-approached the issue. First, I put the gun back to stock. Second, I bought some factory ammo – Federal 180FP. Third, I decided to deal with just one mag – mag “#2,” I have them marked. #2 was picked at random.

Out to the range with five types of ammo: Factory 180JHP PPU (de-tuned, OAL 1.250”). Factory Federal 180FP (the ammo I just bought – de-tuned, OAL 1.247”). Factory 180XTP HPR (it’s a boutique company that uses Hornady XTP’s, and they’re hot, OAL 1.262,” SAAMI max is 1.260”). The Montana Gold 180JHP handloads previously mentioned. And an X-treme 180RNFP handload, using AA#7 (de-tuned, OAL 1.245”)

The result was basically the same: Rounds two, especially four, and five would “hang up.” I only had a couple hang ups after round five. Most of the time, when round five hung up, it would detach from the extractor claw; so, I would have to drop the mag and let the round fall out through the well. But that happened to just round five.

Noteworthy, was that the de-tuned ammo did better – far fewer hang ups. The hot stuff (HPR, and Montana Gold) would hang up much more.

I brought two 10rd mags with me. Both performed flawlessly, with all the ammo.

So I’m not seeing much rhyme or reason here – other than the mags, and softer ammo tends to do it less.

I also brought my Glock 29 with me. If functioned flawlessly with all ammo, with a Lone Wolf barrel and tungsten high-strength guide rod/spring.

I generally try to fix this stuff on my own. But this one is a bit of a head-scratcher. I know there’s a lot of Glock guys out there who may have something to share. Any help would be appreciated. Thanks.

[Mosin44az]

Are those 15 rounders Glock mags?

I have had trouble with HPR.

You sound aware of OAL. I have found hangups to be caused by longer rounds.

[Nick_C_S]

Are those 15 rounders Glock mags?

Yes. The problem I'm having is with 15 round mags. The 10's work fine. The HPR bullets didn't give me trouble with the 10 round mags. Only the 15's. But the HPR's aren't the problem. The problem occurs with all the ammo I tested.

[JohnKSa]

That's a puzzler.

Take your extractor out and check it and the extractor plunger/spring/plastic "bearing" assembly carefully to make sure everything looks good and is clean and is installed properly. The spring and plastic bearing go to the rear with the plastic bearing touching the plastic-coated cover plate and the metal plunger will go forward and touch the back of the metal extractor.

Sort of a shot in the dark, but I can't think of anything else.

[totaldla]

Take the 15 rounders apart. Clean them. Personally, I would lube the inside of the body with Johnson's Paste Wax or Lucas car wax spray. (I know some folks are going to disagree). Reassemble and give it a try.

If the 15 rounders run fine now, the problem is likely weak springs or wonky follower.

One more thing: if you bang on the bottom of the mag, the jam will chamber and you can keep shooting. A good failure drill

Hope this helps.

[44 AMP]

IF everything worked before with no issues and the only thing changed is the magazine, then its likely not the gun, but the magazine.

WHY the mag is doing what it does, is a mystery, I've got no clue. IF they're under warranty, contact the maker. Shoot the problem mags in a different pistol, see if the problem goes with the mag, or not.

Mark the problem ones and relegate them to plinking use.

lots of possibilities, no real answers, or even any idea which direction to go, sorry.

[JohnKSa]

OP states it happens with all 4 of his 15rnd mags.

"I quickly bought four 15rd mags for my G20."
"There also seemed to be no co-relation to which mag – they all seemed to do it."

[Webleymkv]

Strange as it may sound, I bet if you put stiffer magazine springs in it it will alleviate the problem. I had the same sorts of problems with my S&W M&P 2.0 10mm except I had one mag out of three that didn't malfunction. What I finally discovered was that wit Underwood or my full power handloads, the slide was outrunning the magazine springs and causing weird malfunctions. A 22 lb guide rod/spring assembly from Galloway precision and new mag springs from Springer Precision solved the issue.

[The Verminator]

Originally Posted by Webleymkv

Strange as it may sound, I bet if you put stiffer magazine springs in it it will alleviate the problem. I had the same sorts of problems with my S&W M&P 2.0 10mm except I had one mag out of three that didn't malfunction. What I finally discovered was that wit Underwood or my full power handloads, the slide was outrunning the magazine springs and causing weird malfunctions. A 22 lb guide rod/spring assembly from Galloway precision and new mag springs from Springer Precision solved the issue.

Put stiffer mag springs in a Glock?

They're already so stiff that you can hardly get them loaded.

[Nick_C_S]

Take your extractor out and check it and the extractor plunger/spring/plastic "bearing" assembly carefully to make sure everything looks good and is clean and is installed properly.

I'm rather leaning toward the extractor too. Something about the higher capacity mags putting the condition "over the top" and manifesting itself.

I don't know how to remove the extractor assembly. Nor do I know what I'm looking for (other than to clean everything). I guess U-tube is my friend.

[totaldla]

The distance from cartridge to extractor doesn't vary whether 10 or 15 round mag.
Since Glock changes followers without warning, the 10 rounders may have a different follower than the 15. You could always pull the follower out of a 10 and put it in a 15.

Too tight or too loose an extractor usually causes failure to extract (or flinging brass on your head) not failure to feed.

Btw, when you say "detach from the extractor", I'm assuming you are talking about an unfired round, not an empty.

Focus on your mags (or don't).

[totaldla]

Originally Posted by 44 AMP

IF everything worked before with no issues and the only thing changed is the magazine, then its likely not the gun, but the magazine.

WHY the mag is doing what it does, is a mystery, I've got no clue. IF they're under warranty, contact the maker. Shoot the problem mags in a different pistol, see if the problem goes with the mag, or not.

Mark the problem ones and relegate them to plinking use.

lots of possibilities, no real answers, or even any idea which direction to go, sorry.

I have seen this sooooo many times with double-stack pistol magazines that I always clean them first.

Glock magazines are pretty robust - very hard to bugger up. Can't say that about MagPul Glock mags and others.

[The Verminator]

Are your 15 round mags hard to load like all Glock mags?

It sounds like reliability gets better as spring tension decreases.

Load just five rounds and see what happens.

Also.........

Buy a new 15 round mag to compare with your others.

Maybe you got into a bad batch.

[Jack Ryan]

Put everything back with all the stock parts in it the way it was designed to work.

IF you still have problems, seat your reloads .010" deeper.

[stagpanther]

Achilles heel of Glocks has always been the angled presentation of the cartridge to the chamber IMHO. I've put together several PCCs and the Glock-patterned magwells are always the most problematic to get working reliably. Unless that cartridge gets fed just right--you're going to get what is happening to you. That said--i have two Gen 3 20 SFs, one of which I've configured just like your's--if you let them climb on you while firing hot loads (aka "limp wrist") that can cause malfunctions. Those plastic magwells can get "loosey goosey" over time; I'm guessing your problem probably lies with how the magazine sits in the grip. You might also want to try switching your mainsprings out to +/-; I got a complete set from Lone Wolf for that purpose.

[Shadow9mm]

Well, you have ruled out the barrel and spring by swapping in the originals

Were there any feed angle changes in gen 4 and 5 mags?

were the 15rnd mags new when you bought them?

[Nick_C_S]

Btw, when you say "detach from the extractor", I'm assuming you are talking about an unfired round, not an empty.

Yes. And I'm not 100% sure that's what's happening with round five. I just know that simply pulling the slide back about 1/4" doesn't work (like with the other hang ups). When that condition occurs, the fix is to drop the mag and allow the unfired round to drop out the well (inverting the gun might work too, but that's obviously a dumb thing to do).

Are your 15 round mags hard to load like all Glock mags?

Yes. And they are OEM mags, btw. Also, I bought them all at once from Sportsmen's. So a "bad batch" is possible. But I won't be buying more mags at this time.

It sounds like reliability gets better as spring tension decreases.

It would seem that way, yes.

Put everything back with all the stock parts in it the way it was designed to work.

I did. That was my first step, as stated in the original post.

IF you still have problems, seat your reloads .010" deeper.

I've considered that. But that doesn't help me with factory ammo. I realize I can seat factory ammo deeper, but I'm not doing that. It's a Glock. They're designed to run on factory ammo - as countless Glock owners do.

Additional info: I don't have a lot of rounds through this gun. Although I bought it in 2013, I've never shot it much. I bought the Lone Wolf before I ever received the gun (10-day wait period in Ca.). I dropped in the Lone Wolf barrel its second day at the range. The tungsten recoil spring wasn't far behind. In total, I have maybe 1500 rounds though this gun and most of that was with the aftermarked drop-ins. So the original barrel and recoil spring are near-new.

[The Verminator]

Why don't you buy a 15-round mag direct from Glock and see if it works.

Then you'd know if your other four are from a bad batch.

It sounds like your rounds are popping up too easily and going awry.

[tangolima]

The feed lips of the magazine control the round's attitude, which determines the feeding. 10-round and 15-round mags have the same body, but different springs and different followers. Try swapping spring/follower. Possibly those 15 rounds have problematic feed lips.

-TL

Sent from my SM-N960U using Tapatalk

[Koda94]

See if you can find some Gen3 15rd Glock magazines to match your Gen3 pistol.
I also agree try putting a follower from one of your 10rd mags into one of your problem 15rd mags and test that.

[Nick_C_S]

Appreciate everyone's patience.

I was rummaging around in one of my safes about a week ago and found two 15-round Glock Store magazine "rebuild kits." These were Ca legal back when I bought them - before they closed the loophole. Anyway, I left them in their original packaging (in case I was ever accused of assembling them), and forgot I even had them.

As a "rebuild kit," there were dismantled. I assembled one. The follower is definitely different that my other 15-round mags. The follower looks much more like the followers in my 10-round mags - but slightly different. So that certainly looked encouraging.

Also, I removed the extractor, cleaned it up real good (it wasn't that dirty) and returned it.

Off to the range . . .

Unfortunately, it didn't go well. With the Federal "de-tuned" ammo, it jammed on rounds 4 and 6 - just like the others. I then topped it off with the hot HPR ammo - exact same result. Then I topped it off with more HPR ammo, and replaced the stock spring with the stronger tungsten unit - exact same result. I packed it up.

So . . . I guess I'll try putting the 10-round followers into the 15-round bodies, but I have no other ideas.

[L-2]

I don't always have much input on internet/remote gun problems as I often need to see & handle the problems in-person to figure stuff out. For Post 21, I want to point out the latest/current 10mm Glock follower would be a #4 follower. Any lower number could be of concern. I saw no different follower for a 10-round or 15-round 10mm Glock mag in Glock's parts list.

There are different mag springs between the 10-round and 15-round mags, however.

I'm also unaware of Glock selling rebuild kits, although any supplier could have put together such a kit, but unknown if the kit used actual Glock-branded parts.

Regardless of the follower number, since you also own a G29, you might try the follower from one of the G29 mags.

My only 10mm Glock was an older G29 (don't remember the Gen, but it could have been a Gen2) which had intermittent ejection issues (I called it a horizontal stovepipe) which I never could personally fix after buying and substituting in various new parts.

If the subject G20SF, I suspect Glock's Armorer would likely replace every part other than the frame, slide, and barrel, noting any possible differences with the old parts. It's possible some of the present parts could've been superceded/upgraded or somehow wrong for the G20SF model. The Armorer would then test fire a limited number of rounds to determine if reliable. The Armorer might have even test-fired the gun prior to working on it.

Another Glock I had, a G30Gen4, started experiencing failures to feed until I noticed the frame was cracking over the locking block pin area. Glock replaced that frame and the problem was fixed (probably too much frame flexing when firing the gun).

That's all I've to say on this issue. Let us know if the cause is ever diagnosed & fixed.

[DaleA]

I've got no advice but I thank you for coming back to the thread and telling us what you did. I suspect many folk follow threads but don't post to them and appreciate getting updates.
Good luck.

[Nick_C_S]

For Post 21, I want to point out the latest/current 10mm Glock follower would be a #4 follower. Any lower number could be of concern. I saw no different follower for a 10-round or 15-round 10mm Glock mag in Glock's parts list.

Looking on the "slide lock tab" (don't know what else to call it), the 10-round mag has a "3" on it. The 15-round mag I purchased after moving to Idaho has a "4" on it. The 15-round mag from the kit has a "2" on it.

I'm also unaware of Glock selling rebuild kits, although any supplier could have put together such a kit,

I purchased the kits from The Glock Store. Although they likely assembled the kits themselves for sale, all of the components certainly look to be OEM parts. The Glock Store is a fairly reputable company by all accounts I know of. I know all of that means little. My only point is that I didn't get the kits from Guido out of the trunk of his '68 Cadillac.

I just went on Midway's site and searched for Glock mags. They are offering a follower that the pic looks absolutely identical to the one(s) in my 15-round mags - with a "4" on it. For whatever that means.

[reynolds357]

Originally Posted by The Verminator

Put stiffer mag springs in a Glock?

They're already so stiff that you can hardly get them loaded.

Yep.Stretch one and try it.