Glock 20 Gen 4 failure to feed Underwood 180 TMJ

[Dave84]

I've had some problems with Underwood 10mm in the past. One was caused by an overly tight Stormlake barrel. In stock configuration the gun feeds very near 100%. Newest issue from me messing around is my Arredondo mag extension is feeding really spotty.

[Geeman]

These pics show what happened when I tried Underwood 180gr TMJ in my stock G20 gen4 other day...shot maybe 10 rounds and over half had malfunctions.

However, Underwood 200gr TMJ did much better - shot 50 rds with one failure to extract.

Have not experienced any problems with Double Tap 200gr wfngc hardcast, but have only shot 10 or so as they're so pricey.  The lower power stuff (PPU, Armscor) feeds fine.

I'm thinking of trying an aftermarket gen4 RSA but for the life of me can't find the thread I saw last month with that info. Seems there were 2 companies now making gen4 rsa's - anyone know who?

Your problem is different than what I was thinking.  It seems you have more of an ejection issue than a feed problem.

When I shoot Underwood, my empties wind up 15 ft away, sometimes on the roof of the pistol house.  I'd have someone look at why this is happening. 

Greg

[Driftwood]

I'll throw another possibility out there.  It could be a problem with the ammo.  I have shot many different variations of Underwood Ammo and for the most part, it shoots well out of my G20.  I have had some issues however.  I had some that would not eject the brass at all.  I eventually pulled a few of those rounds to investigate.  Each of the 3 rounds that I pulled required over 20 aggressive hits on a concrete floor to get the bullet to unseat.  I actually bent the steel shaft of my puller.  I am fairly new to reloading and using a bullet puller, but it seemed to me that the rounds were crimped way too tight.  The bullets themselves were compressed severely where they were seated into the case.  I didn't measure the diameter or take photos, but it just didn't look right.  I have taken apart other rounds from Underwood, Doubletap and other off the shelf brands and have never had that much difficulty pulling a bullet, nor have I seen a bullet look like that. 

The remainder of the box was returned to Underwood and replaced with perfectly functioning ammo.  I'd recommend that anyone having issues with Underwood Ammo give Kevin a call.

[4949shooter]

My opinion...

With  the full power ammo and the stock 17 pound spring, I believe the slide impacts the rear of the polymer frame causing it to flex slightly, which I believe creates a failure to extract issue. The solution to the problem with my G20 was to get a 22 pound RSA. This solved the problem. I think the issue is exacerbated if the shooter keeps a tight wrist lock when they are firing. The problem did not occur for me with the stock spring while being fired one handed. The extra recoil in the upwards direction I believe takes the stress off the frame.

Just my own experience and opinion, of course.

[The_Shadow]

I'll throw another possibility out there.  It could be a problem with the ammo.  I have shot many different variations of Underwood Ammo and for the most part, it shoots well out of my G20.  I have had some issues however.  I had some that would not eject the brass at all.  I eventually pulled a few of those rounds to investigate.  Each of the 3 rounds that I pulled required over 20 aggressive hits on a concrete floor to get the bullet to unseat.  I actually bent the steel shaft of my puller.  I am fairly new to reloading and using a bullet puller, but it seemed to me that the rounds were crimped way too tight.  The bullets themselves were compressed severely where they were seated into the case.  I didn't measure the diameter or take photos, but it just didn't look right.  I have taken apart other rounds from Underwood, Doubletap and other off the shelf brands and have never had that much difficulty pulling a bullet, nor have I seen a bullet look like that. 

The remainder of the box was returned to Underwood and replaced with perfectly functioning ammo.  I'd recommend that anyone having issues with Underwood Ammo give Kevin a call.

Driftwood, when you use your kinetic bullet puller try hammering it against the end grain of a piece of 4x4, this will help your puller and its operation as such.  I use a piece of 4x4 about 20" long and stand it on end, be sure the cartridge is securely held by the puller, and give it a whack trying not to let it bounce.  I usually start with easy taps with non cannelured cartridges, and heavier taps using heavier crimped bullets.  If you have read in the pull-down sections here on this forum, you will know I pull a bunch of stuff.  Most kinetic type pullers you can use the shell holders from die sets in place of the little 3 piece aluminum jaws. (Mine are being close to worn out with over 35 years on this RCBS kinetic puller.)

So give this method a try see if it will help you out!  Best regards! 

[Driftwood]

I'll throw another possibility out there.  It could be a problem with the ammo.  I have shot many different variations of Underwood Ammo and for the most part, it shoots well out of my G20.  I have had some issues however.  I had some that would not eject the brass at all.  I eventually pulled a few of those rounds to investigate.  Each of the 3 rounds that I pulled required over 20 aggressive hits on a concrete floor to get the bullet to unseat.  I actually bent the steel shaft of my puller.  I am fairly new to reloading and using a bullet puller, but it seemed to me that the rounds were crimped way too tight.  The bullets themselves were compressed severely where they were seated into the case.  I didn't measure the diameter or take photos, but it just didn't look right.  I have taken apart other rounds from Underwood, Doubletap and other off the shelf brands and have never had that much difficulty pulling a bullet, nor have I seen a bullet look like that. 

The remainder of the box was returned to Underwood and replaced with perfectly functioning ammo.  I'd recommend that anyone having issues with Underwood Ammo give Kevin a call.

Driftwood, when you use your kinetic bullet puller try hammering it against the end grain of a piece of 4x4, this will help your puller and its operation as such.  I use a piece of 4x4 about 20" long and stand it on end, be sure the cartridge is securely held by the puller, and give it a whack trying not to let it bounce.  I usually start with easy taps with non cannelured cartridges, and heavier taps using heavier crimped bullets.  If you have read in the pull-down sections here on this forum, you will know I pull a bunch of stuff.  Most kinetic type pullers you can use the shell holders from die sets in place of the little 3 piece aluminum jaws. (Mine are being close to worn out with over 35 years on this RCBS kinetic puller.)

So give this method a try see if it will help you out!  Best regards! 

Thanks Shadow.  I do typically use a block of wood to pull bullets, though I haven't tried it as you described using the end of a 4x4.  I will definitely give that a try.  The point I was making was that with those specific Underwood loads, striking wood did not work.   The only way to get the bullet free was to hit concrete.  No other ammo has given me any problems.  In this case, even Kevin at Underwood admitted there was definitely a problem with the ammo, though he didn't specifically say it was over crimped.  That is just my assessment.

[DAVIDF]

I have a Glock 20 gen 4 and this is my first Glock. I absolutely love the gun it handles great, however as soon as I wanted to shoot real 10mm ammo I had multiple jambs. I had minor work done to the gun, lighter trigger pull, night sights, and slide release done by Glockmeister, who told me the std double spring should handle all ammo hot or light. Any one had this problem? Or found the cure?

I had the same issues with a Gen 4. http://10mm-firearms.com/10mm-semi-auto-handguns/problems-with-failures-to-feed-with-underwood-ammo-gen-4-glock-20/ I received a lot of help from lots of people on this forum. I tried heavier Gen 3 RSA's with an adapter & the Rachis RSA which is designed specifically for Gen 4's. Nothing seemed to help. In fact, the condition seemed to deteriorate & eventually the gun was not functioning with mid-level loads with a full magazine. It would function OK with only 5 rounds in the magazine, but once it was loaded more than that it would frequently fail to feed.

The cure was that Glock replaced it with a gun of my choice. I chose a Glock 20 Gen 3. It has worked flawlessly. I had to send it to them twice but in the end everything is good. Seems like some of the Gen 4's work flawlessly & others have issues. Hope everything works out for you.

[Gviz]

Good info on here.  Just bought my first 10mm, Glock 20 gen 4, last week.  I shot a total of 40 rounds (filled the magazine 4 times with 10 rounds) and had 3 FTF's.. not a good percentage as far as reliability goes, especially for a Glock.  I was using PMC bronze 200 grain ammo.  Other than that it was a blast to shoot 

[Dave84]

Good info on here.  Just bought my first 10mm, Glock 20 gen 4, last week.  I shot a total of 40 rounds (filled the magazine 4 times with 10 rounds) and had 3 FTF's.. not a good percentage as far as reliability goes, especially for a Glock.  I was using PMC bronze 200 grain ammo.  Other than that it was a blast to shoot 

I'm surprised by this. Give it more of a break-in period before you can expect 100%

[G20g4]

I received two recoil springs from Spinco took my gen 4 to the range. Still having failures with the 180 TMJ. I have some 165 TMJ on order. I will see how they work. If nothing better next phase will be to call Glock or just trade it back to Cabelas and get another 20 or different 10mm altogether. So far I am pretty disappointed with Glock. It fires weak ammo great. Maybe it's the 180 Underwood.  I have spoken to Kevin if that's the problem I will just stay away from the 180. I prefer a lighter faster bullet anyways, I don't hunt with it so over penetration would be a concern.

[krafcheck]

maybe gen 4 is finicky and needs several hundred rounds through it?

when i replaced my spring to 22 pounds it still happen for a little while then got better and better.  i have a captured rod so putting the recoil spring was ruff but when done the spring was all "wiggly" put when i was done and cleaning the spring had straightened out.  i still need to shoot it more and make sure it is taken care of for my comfort.  i have the gen 2 model

[Intercooler]

  I don't think the amount of rounds is going to change the function.

[pacapcop]

These Gen4's seem to suffer the new car model first yr syndrome. I run the Gen 3 with a steel guide rod and 22lb spring from Wolff. Eats it all.

[mt10mm]

I agree with IC, some guns just don't like a certain type of ammo.

[G20g4]

Been to the range and 3 of the 4 boxes fed fine. No jams, last box had multiple jambs. Fired one box of 165 TMJ zero failures. Maybe it is breaking in or got a bad batch. Will definitely continue to shoot Underwood ammo.