Need advice - sell (and rebuy) Glock 20 or continue to troubleshoot ammo?

[Brian B.]

Thanks for the thoughts. Ultimately, I decided to prioritize ammo feeding. My Gen 3 Glock 20SF can't feed the ammo that I want to shoot, and has failed with several different versions of that ammo, so that gun is sold. I appreciate the feedback from people saying that their Glocks couldn't feed certain 180 grain loadings while the 165 grain ammo worked. However, this gun is for bear and moose protection, so I really bought it to shoot 180-220 grain bullets.

I've got a Gen 4 Glock 20 coming to my FFL this week, so I will be able to test a second gun with this particular Underwood 180 grain TMJ ammo. I will update this thread with what I find. If the second gun fails with the same boxes of ammo that were making my first gun fail, then I'll contact Underwood and try to figure something out. I know you can't return ammo, but I've got like 700 rounds of this stuff, and if a large quantity of it is out of spec, then surely they will want to make that right.

Congrats on the new gun. You should let me take some of that ammo off your hands 

[The_Shadow]

With the slide off of your guns that are having issues, have you tried sliding the cartridge up from the bottom and under the extractor and check it for fitment?  The cartridge should slide in without much resistance, but should be held by the extractor.
In rare cases the wrong extractor may be placed in the firearms or the tolerances may be slightly off and can be too tight or too dry of lubricant or debris.  However it may be with all ammo and not just some.

The impulse of some of the high performance ammo like Underwood and Double Tap can accelerate the slide to such an extent it will not pick up the ammo and push it forward and up into the chamber. 

Things that come to mind are magazine follower & spring not pushing up the ammo smoothly or in time for the slide to push it forward at the right time to transition to the chamber.

I run the Wolf Non captive 22lb for my G-20SF and I have tried to limp wrist, gangsta shooter (gun laid on its side) and even shooting it upside down trying to induce a failure to feed.  However thankfully my runs flawlessly with anything I have fed it!

[DM1906]

You might also check the magazine presentation and ejector alignment. With the magazine full, the top cartridge should be (almost exactly) parallel with the mag base (make sure the cartridge is all the way rearward in the mag). If this is correct (or after it's corrected), disassemble the pistol, set aside the slide, barrel and spring, and insert a full mag into the frame. The top cartridge or magazine lip should not contact the ejector, but be close enough you can force contact with firm upward force on the mag. The extractor should be slightly angled inward at the tip-end, and should be positioned above the case at about 10:30 (if it doesn't interfere with the slide during assembly, it is correct), and the tip of the ejector should be no more than 1/4" forward of the case head (typically .200-.240"). If either of these are incorrect, they can cause feeding and/or ejection issues, especially when coupled with any of the conditions previously mentioned.

[t6t0]

Posting an update: I just picked up my new Gen 4 Glock 20 and put 60 rounds through it using the exact boxes of Underwood ammo that were giving me multiple failures per magazine with my other gun. I didn't have a single malfunction, which I count as a marked improvement. Barring any changes to reliability that result from the gun breaking in, it looks like the issue I was having was a gun issue and not purely an ammo issue. Going to count this as "problem solved."

[4949shooter]

Congrats and well done. 

My Gen 4 20 is my favorite.

[Brian B.]

Posting an update: I just picked up my new Gen 4 Glock 20 and put 60 rounds through it using the exact boxes of Underwood ammo that were giving me multiple failures per magazine with my other gun. I didn't have a single malfunction, which I count as a marked improvement. Barring any changes to reliability that result from the gun breaking in, it looks like the issue I was having was a gun issue and not purely an ammo issue. Going to count this as "problem solved."

Was this original Glock new or used when you initially got it? I'm just curious.

[t6t0]

Posting an update: I just picked up my new Gen 4 Glock 20 and put 60 rounds through it using the exact boxes of Underwood ammo that were giving me multiple failures per magazine with my other gun. I didn't have a single malfunction, which I count as a marked improvement. Barring any changes to reliability that result from the gun breaking in, it looks like the issue I was having was a gun issue and not purely an ammo issue. Going to count this as "problem solved."

Was this original Glock new or used when you initially got it? I'm just curious.

I bought both of them new. The original Gen 3 20SF had problems shooting the 200 grain Underwood ammo pretty much right out of the box.

[chucky2]

You seem to definitely be in the minority in having a Gen3 that a.) had issues and b.) was not relatively easily fixable.  I'd continue to test out that Gen4 G20, they definitely have not been the most reliable with higher powered ammo...

[pacapcop]

I'll go on record that the issue is the TMJ period. Doesn't feed in Glock barrel.

[t6t0]

I'll go on record that the issue is the TMJ period. Doesn't feed in Glock barrel.

I did try shooting the same ammo in my Gen 3 that I sold, with a KKM Precision barrel, and it still jammed.

[Pablo]

It's the ammo, well rather the bullet shape. No doubt about it. In fact, you will notice UW doesn't sell their TMJ 200 or 220 gr 10mm bullet ammo anymore. It was not the OAL, but rather a combination of the length and bullet shape. I like and use UW, but that ammo would not feed in three of my 10mm guns. I could take say 1 each of all the different 10mm ammo I own (over 10 types including my reloads), and in random order fill mags of different guns. Guns, each one, would stop (partially feed) with the UW 200gr (sometimes the 180gr as well)

This is with Glock and S&W and LW and RMW barrels..........(my LW barrel is known tight and it for sure won't take ANY UW)

[Dave84]

It's the ammo, well rather the bullet shape. No doubt about it. In fact, you will notice UW doesn't sell their TMJ 200 or 220 gr 10mm bullet ammo anymore. It was not the OAL, but rather a combination of the length and bullet shape. I like and use UW, but that ammo would not feed in three of my 10mm guns. I could take say 1 each of all the different 10mm ammo I own (over 10 types including my reloads), and in random order fill mags of different guns. Guns, each one, would stop (partially feed) with the UW 200gr (sometimes the 180gr as well)

This is with Glock and S&W and LW and RMW barrels..........(my LW barrel is known tight and it for sure won't take ANY UW)

.        Do they use a different fmj design now?

[Pablo]

Pretty sure they don't sell that ammo any more.

[gandog56]

"3) I do not want to send the gun back to Glock. From what I've read, they don't even recommend using Underwood ammo, so they may not even be able to reproduce the problem at their factory. Add onto that, I'd have no 10mm handgun for multiple weeks in the summer when I do the most backpacking in bear country - NOT an option."

I dont know if this is true, i had not heard this myself,.. But the fact that you shot (only one other brand) DT with no issues combined with your above statement gives you a direction to go IMO.

I don't know, but if I will be in bear country and maybe get into a SHTF situation, I would not be staking my life on an unreliable weapon!

[t6t0]

It's the ammo, well rather the bullet shape. No doubt about it. In fact, you will notice UW doesn't sell their TMJ 200 or 220 gr 10mm bullet ammo anymore. It was not the OAL, but rather a combination of the length and bullet shape. I like and use UW, but that ammo would not feed in three of my 10mm guns. I could take say 1 each of all the different 10mm ammo I own (over 10 types including my reloads), and in random order fill mags of different guns. Guns, each one, would stop (partially feed) with the UW 200gr (sometimes the 180gr as well)

This is with Glock and S&W and LW and RMW barrels..........(my LW barrel is known tight and it for sure won't take ANY UW)

]

Hmm. I don't think it's the ammo. My original Gen 3 choked on BOTH TMJs and XTP hollow points. My Gen 4 can feed both.