Glock 20 Gen 4 Problem

[The Last American Hero]

C.O.A.L too short? I thought a 10mm Glock could eat .40 no prob.

"The last round always seem to sit differently on most Glock magazines. What is the C.O.A.L. of the ammo you are shooting? It is very possible it is on the shorter side of the acceptable length causing the round to hang up on the bottom of the feed ramp as its being chambered long enough to have the slide run it over and not allow it to go into battery. The C.O.A.L. should be 1.250" to 1.260" anything shorter cause the type of issues you are having. "


Will a G20 only eat .40 if you change barrel and mags?

[Bill Steele]

"The last round always seem to sit differently on most Glock magazines. What is the C.O.A.L. of the ammo you are shooting? It is very possible it is on the shorter side of the acceptable length causing the round to hang up on the bottom of the feed ramp as its being chambered long enough to have the slide run it over and not allow it to go into battery. The C.O.A.L. should be 1.250" to 1.260" anything shorter cause the type of issues you are having. "


Will a G20 only eat .40 if you change barrel and mags?

My G20's and G29's will feed 40S&W all day long.

I think the OP's issue is with slide lock back with one round still in the magazine, not a feed failure per se, at least that is how I read the thread. Confusing though, the reference to FTF.

[H K corporate assassin]

Simply try different ammo.

[momokie]

Update

I've now tried

15 round factory mag
10 round factory mag
15 round factory mag blocked to 10 rounds
10 round factory mag with Wolff 10% spring

I shoot mostly UW 165 TMJ, but have also tried UW 180 TMJ, UW 150 Nosler, and UW 135 Noslers.

The last round in the mag still fails to feed almost every dang time after a previous round has been cycled.

Completely stock aside from the OEM extended slide release (Glock 20 SF version)

nice info..
I have a G29 with a similar setup, just different brand aftermarket connector, and I'm using the factory firing pin spring. I don't shoot anything but my reloads, but do keep 'er loaded up with some DoubleTap 165gr rounds. Glad you like the G29 and 10mm.

You'll get more consistent performance with that G20 mag in the G29, if you use a sleeve, like the A&G sleeve...prevents "rocking" of the mag in the mag well.

[PandaBear]

I have the 20 and not the 29, but I have heard others have the issue you just described.

I'm not interested in shooting watered down 10mm so Underwood or PBR is the best value for my money until I can get a reloading setup.

[YellowTT]

Im having similar issues only with Underwood ammo. At the moment I'm have the tpm double guide rod spring. Phantom trigger. Kkm barrel. And some of the polished bling stuff. Slide jams and bullet gets caught at same location shown in pic posted by op.

[YellowTT]

Finally solved the problem with my g20 3rd gen. Same thing was happening till yesterday, was at the range doing some quick follow up shots and the jam started happening alot sooner than before. Took slide off and the spring of the slide catch was not all the way to the left where it should be. Moved it over to its correct position and was able to rapid fire with no malfunctions. Going back in a couple of days to retest

[J-cat]

I run a 22lb RSA on my G20SF to help slow things down with hot loads, but I am not getting how the RSA will effect the premature lock back. In my experience that is always caused by interference of the bullet ogive and the slide lock, or the shooter riding the slide lock up with his/her grip. If anything, I would expect the higher felt recoil with the heavier spring to make any bullet movement forward in the magazine worse.

Not arguing, just thinking out loud.

More slide velocity means harder frame slap means more frame vibration which can induce the slide stop to jump up and lock the slide.

[dwtt]

I have never had this problem with my 3rd generation Glock 20, with 10- or 15-rd magazines. My gun is stock except for a Storm Lake barrel, and have the stock slide stop, magazine release, and springs. Maybe the OP should try installing the stock components and seeing if that solves the problem.