Problems with failures to feed with Underwood Ammo, Gen 4 Glock 20

[DAVIDF]

sqlbullet,  no I have no issue with you raising that question. I have not had any issues with FTF with any of the other autos I've used with the exception of a magazine issue on an old WWII surplus 1911 and loads that were too light with my Glock 9mms (loads like the 115gr Federal & even lighter reloads that seem to be a common problem). And, not with my Glock 20 with light loads. I thought that if someone limpwrists too much, it is more likely to cause malfunctions at lighter loads than heavy loads. Is that correct, or could it cause problems on the other end of the sprectrum with very heavy loads?

[sqlbullet]

Yes...

My line of thinking was that maybe if there was a grip issue combined with extra recoil  your hands might be shifting enough to rub the slide or push on the slide stop slowing the slide down prematurely.  This is different than the typical limp-wrist scenario, but was a thought that ran through my mind.

[RMM]

sqlbullet, I think that you are on to something.  I think that you should definitely check to make sure that you aren't "riding" the slide or slide stop with your fingers. 

As far as limp wristing goes, a "limp wrist" malfunction is actually less likely to occur with high power ammo. 

I would also be looking at the gun.  When you cycle it slowly by hand does it seem normal?  Does the extractor grab and hold the bullet fairly tight against the breech face? 

Just some thoughts that I had.

[DAVIDF]

You all are thinking along the same lines that I was while at the range. I tried different hand positions from thumbs higher to lower to make sure I wasn't hitting the slide stop or dragging thumbs along the slide, etc. Nothing seemed to help.

When I cycle it slowly it does appear normal. I'll take another look when I get home. I'll specifically look at the extractor. The only thing different from other Glocks is that the ejector sits a bit high & gouges the slide cover plate during reassembly.

[RMM]

\ The only thing different from other Glocks is that the ejector sits a bit high & gouges the slide cover plate during reassembly.

That's normal for the G20.  If you pull up on the slide a little bit when you reach the ejector it will go on smoothly.  Took me a minute the first time I took the slide off my G20 to figure out what was going on!

[DAVIDF]

Thanks, good to know. Glock rep was not alarmed at that. Even if I pull it up, it still gouges the slide cover slightly. Whereas my 17 & 26 clear it with no problem.

[Intercooler]

All the ammo arrived today! I took the boxes out and looked them over... pretty 


I see you had a couple marked with length. Are those the ones you want me to shoot some from? I think I can fit it in tomorrow morning. Do you want me to run a special 10 or video any of it?

[4949shooter]

I don't know if limpwristing is the cause with these 10mm Glocks.

Assuming the ammo isn't the problem, when I let my wrist flex a little the gun worked better with the Underwood. When I tightened up my wrist the gun malfunctioned more.

And I shot a lot of Underwood 200 grain XTP one handed (read more wrist flex). The XTP never malfunctioned when fired one handed. This makes me believe the slide is hitting the polymer frame too hard causing malfunctions when fired two handed (read tighter wrist and less flex). It's just an opinion I have now, but this condition may be increased by whichever level Kevin is loading the 180 grain tmj to. The 200 XTP worked a lot better than the 180 grain with a two handed hold.

This condition still may be exacerbated by the ammo.

Edit: There was a member over on Glocktalk who had a similar problem and brought this to my attention.

[Intercooler]

Headed out in about 30 minutes to test them out.

[4949shooter]

Sounds good we'll be waiting!

[DAVIDF]

Intercooler, any of them will do. The boxes that had oal listed on them were a couple thousandths longer than the others so I marked them. There were 2 boxes I believe that were like that. One box of the longer ones worked well with the stock springs, however, I only fired about 20 rounds or so. I had issues with the same box when I tried it with the tungsten guide rod & 22 pound springs. All the other boxes I tried were problems with both sets of springs.

[Intercooler]

   Always need another excuse to enjoy a weather perfect day shooting some ammo up!  I took those two marked boxes with me for the testing. I figured you had measured them and knew what they were. To start off I warmed up with American Eagle all four 10mm's (Dan Wesson Razorback, EAA Witness Hunter, EAA Witness Match, S&W 1006). All shot perfect with no issues and the Witness pistols are using the red follower magazines which some folks have issues with. Now the battery of tests:

Razorback 1.244-1.247 5 rounds. No malfunctions
Match 1.244-1.247 5 rounds. No malfunctions
Match 1.245 5 rounds. No malfunctions
Hunter 1.244-1.247 5 rounds. No malfunctions
Hunter 1.245 5 rounds. No malfunctions
Razorback 1.244-1.247 5 rounds. No malfunctions. I ran 2 more trying to be a total limp wrist and both malfunctioned angled down needing me to tap the slide forward. This pistol is still tight and lightest which is the best to induce this and it worked!
Razorback 1.245 5 rounds. No malfunctions
1006 1.244-1.247 5 rounds. No malfunctions
1006 1.245 5 rounds. No malfunctions
Hunter 1.245 5 rounds. No malfunctions

   I personally look at ammo as if it is within spec it should run. Some pistols are more sensitive to the dimensions I'm sure. Next on the list is am I doing anything wrong? If no, then start digging into the pistol looking for stuff. If I had to guess the ammo you have coming your way won't fix the issue and hope to hear your results.

[4949shooter]

Thanks for posting your results, IC.

David, I would be curious to know if your Glock will work with the hotter ammo when fired one handed.

[DAVIDF]

Thanks Intercooler, I didn't expect you to have any issues. I'll try the ammo you're sending as well as some PMC or Armscor. From that, I will get an idea of where it begins to malfunction.

4949shooter, yes I will try & let you know.

[DAVIDF]

Went to the range today with the ammo that Intercooler swapped with me plus bought some PMC 170 gr HP. Intercooler sent me American Eagle 180gr fmj, PBR 165 & 200 gr fmj, & Underwood 180 gr fmj Delta lite loads. I also again tried a few of the Underwood 180gr TMJ.

I tried all of the loads with both the stock springs & a Glockstore tungsten guide rod w/22lb springs.  I  went in order with what I believed were the lightest to the hottest (American Eagle, PMC, Underwood 180gr Delta Lite, PBR 165gr, Underwood 180gr TMJ, PBR 200gr).

The results were pretty close to what I expected, perhaps a bit better. The American Eagle, PMC, & the Underwood Delta Lite loads all functioned flawlessly. I was particularly happy with the Underwood Deltas. They may be the most accurate semi-auto handgun round that I have used in any pistol. These are one hole groups in my pistol as long as I do my job, which doesn't always happen

At the next level something interesting began to happen. With the PBR 165gr they functioned flawlessly as far as feeding, but almost always locked the slide back when one round was left in the magazine. Happened with at least 2 of my 3 magazines. I failed to keep track of whether it occurred in the 3rd. This also happened consistently with the heavier loads. I kept my thumb well away from the slide stop so I don't believe it was my hand hitting it under recoil.

The Underwood 180gr TMJs still gave me consistent problems with failing to feed. Every failure was with nose of the bullet lodged high at the top of the chamber. Again, the stock springs actually worked slightly better than the tungsten guide rod with 22lb springs. This load is the second most accurate load behind the Deltas.

Finally, the PBR 200gr FMJs were the worst. Pretty consistently failing to feed with the nose of the bullet again lodged high at the top of the chamber.

I'm happy that at least the Underwood Delta Lites worked good & were extremely accurate. This is about the level I would like to handload once components become more readily available. But, I will probably call Glock on Monday & ask them to take a look at it. Although they don't recommend loads as hot as Buffalo Bore (they didn't list Underwood by name) I haven't seen other Glock 20s have these issues.

Intercooler, thank you again for swapping ammo with me. This has been extremely helpful to me & it was really great getting to try these various loads when it is so tough to acquire a variety of ammo.