Glock fans: Glock 21 Gen 4 trigger not resetting (stock connector)

[Tripper]

what other glocks you have
make sure the seer is engaging the rear of the trigger bar, that the trigger bar isnt bent, causing the seer not to connect
do you have a compatible striker/Firing pin spring to exchange (any glock firing pin spring will work)

if you have another upper to put on it, at least you could narrow the problem down to upper/lower

[FUBAR]

You didn't install the trigger return spring properly. Disassemble it and re-assemble taking close attention on how the spring is installed. If you feel you put it on correctly, post a pic to verify.

[FUBAR]

It should look like this

[_TomT_]

If he installed the trigger return spring incorrectly than this problem would have persisted even when dry firing. OP said he didn't experience this during dry-fire, only when the gun is cycling real ammo.

[axhoaxho]

OP, like folks said, make sure the whole 'Trigger-Spring/Connector/Trigger-Bar' thingy was installed/seated properly.

In addition to what have been mentioned, also make sure the Connector was seated completely-inside-through the Trigger Mechanism Housing (if in doubt, poke it out with a Glock tool, clean any debris, and reseat it.) Make sure the Connector provides spring-tension to push the rear of Trigger Bar away from the right side of the Trigger Mechanism Housing.

Also double-make-sure the Trigger Spring is 'hooked' properly in the Big-S-Small-S (in Glock Armorer's term) Trigger-Bar/Trigger-Mechanism-Housing assembly. Check the Trigger Spring if it is 'in good form without damages.'

Checkout this video from 1:15 for reference. Best luck troubleshooting.

[vintagearms]

That's what I thought at first too and it makes sense it's not the glock because this isn't a common issue unless you change out the connector or put in a spring incorrectly. So it makes sense that it's the ammo... but how could the ammo cause the trigger to not reset?

timing of the slide causing ejection but not reset. I would get some good factory ammo and try that. If not, have someone else shoot it and see if it can be replicated. Im not saying Glocks are never at fault, but ammo does play a big part with issues.