Glock 20 Gen 4

[PandaBear]

Hello

I have a 100% stock Glock 20 Gen 4 with the up-to-date parts (extractor, RSA, trigger bar).

First outing: 120 rounds down the pipe (Underwood 165 TMJ), I had multiple FTFeed the last round of all 3 10-round blocked magazines.

Second outing: 80 rounds of UW165 down the pipe with only 1 FTFeed the last round.

Since I'm planning on shooting mostly hot ammo I'm planning on swapping out the stock recoil spring and going with a Gen 3 20-22lb recoil spring. Does anyone know if those Gen 4 adapters that allow you to use Gen 3 recoil springs work?

I can live with the last round of the magazine FTF. I'm also curious to know how well the Gen 4 stock recoil springs would hold up over time with the hotter ammo.

[DAVIDF]

Yes, the adapters that allow you to use Gen 3 RSA in a Gen 4 will work at least sometimes. I had a Gen 4 that was having FTF's with a variety of ammo. It did work better with a Gen 3 spring & adapter. However, it function even worse with an adapter and an aftermarket RSA from the Glockstore with a 22lb spring. You'll just have to try and see how it does.

My guess would be that the stock Gen 4 springs would hold up fairly well over time. But that is just a guees.

Glock replaced my Gen 4 with a Gen 3 that is working excellent so far.

[445 supermag]

Replace the slide stop lever and the slide lock spring and that should fix your issues.


I had the same problem  but a Gen 3 glock 20.   That last round would lock the slide back as if the mag was empty.

I changed those two things after a talk to an armor at the GLOCK STORE and all has been well so far.  But granted I have shot a lot of ammo since.  But so far so good! 


It drove me nuts (I guess my OCD) knowing I still had one round left and my slide was locked open.

Best of luck my friend and keep us posted.    If I run into another problem I will post my situation to find a solution.

Brian

[PandaBear]

@ DAVIDF

I read through your whole thread and the problems you were having. Glad you have a working G20 now. I think I will hold off on getting a heavier RSA for the time being until I can test out different types of ammo.

@ 445 supermag

I installed an extended slide stop release after the first outing and then had 1 FTF on the second outing. My slide doesn't lock back as if the mag is empty. Instead the last round fails to chamber, appears to be facing upwards at a 45 degree angle, and the gun fails to return to battery.

Thanks for the replies. I'll report back when I run more ammo through it.

[DAVIDF]

Maybe a stronger magazine spring from Wolff will help with your issue?

[PandaBear]

All 3 of my magazines are permanently blocked to 10 rounds so I am unable to disassemble them. I'll just continue to put rounds down range and if the problem persists, I'll pick up a 10 round magazine.

[Buckeye 50]

I have put 150 rounds of various brands through my new Glock 20 full size Gen 4 with zero problems (knock on wood).  Love it.  I said I would NEVER have a Glock............ (the check is in the mail, I promise I won't..........)

Love it - make get a 29

[The_Shadow]

I was holding out for the Gen4 G-20 but a fabulous deal on a gen3 SF G-20 presented itself   Jumped on that!

[4949shooter]

All 3 of my magazines are permanently blocked to 10 rounds so I am unable to disassemble them. I'll just continue to put rounds down range and if the problem persists, I'll pick up a 10 round magazine.

I am thinking the problem might be those 10 round blocked magazines. The blocked 10 rounders never seemed to be as good as the standard mags.

Are you in a state where 10 round mags are the only capacity magazines which are legal?

[Buckeye 50]

For what it's worth, mine came with 3 - 15 round mags. NIB.  Must have thought I was expecting problems.

AWESOME product.  The polymer is cheap as crap though.

[DM1906]

All 3 of my magazines are permanently blocked to 10 rounds so I am unable to disassemble them. I'll just continue to put rounds down range and if the problem persists, I'll pick up a 10 round magazine.

Never heard of any Glock mags "blocked" to 10 rounds. The latest 10 round mag I've seen is only about 5 months old, and it's the same as previous Gen 3's. They have a rail stamped into the steel sides, narrowing the stack so it will only take 10 rounds. The 20, 21 and 22 I've seen are the same. They disassemble the same as standard capacity mags, too. The only difference is the mag body and the follower, which has a notch to match the rail. All other parts are interchangeable. Unless they've changed in the last couple months, better have another look.

[PandaBear]

I am in CA so we are only allowed 10-round magazines. My FFL would not let me take the 15-round standard capacity magazines as rebuild kits so they blocked them.

I had 5-10 FTF on the first outing and only 1 FTF on the second outing. Might just need some breaking in. I'm thankful that it's only happening on the last round of the magazine.

I will report back when I take it out for the 3rd time.

[4949shooter]

Are the mags blocked by the FFL or are they blocked by Glock from the factory?

[PandaBear]

Blocked by FFL.

[4949shooter]

That just might be the problem.

I would suggest getting a factory 10 rounder directly from Glock.