Hi guys, I'll really appreciate if someone with more experience can help me to figure out what is causing my new G34 to FTF .
So what happened earlier today - I went to the range to shoot my Glocks - 45 & 34 Gen 5 MOS.
First I've shot around 120rds thru the 45 with no drama but then I've switched to the 34 and FTFs started immediately, 5 in total for about 130rds.
Now some details:
Ammo - CBC 115gr.
Mags used when FTFs happened -  Magpul 17rds, OEM Gen 5 17rds, OEM 19X 19rds

This was the second range session with the G34, the first time I went to the range was about a month ago, the ammo and mags were the same and there were no issues.
After that, I've decided to switch the triggers between the G45 (Agency Arms) and the G34 (stock), being lazy I've swapped the entire trigger group from the G45 including the trigger housing and the extractor to the G34. The G45 has over 5k rounds, 3k of which with the AA trigger with no malfunctions whatsoever. However with the G34 that wasn't the case, as I said there was 5 FTF all of them exactly the same - the round jam about halfway into the chamber.
So I'm trying to figure out the reason for this issue, if it's a user-induced malfunction why it happens only with the G34 and only the second time?
If it's the trigger why it worked for around 3k rounds without an issue on the G45?

Two things I've noticed: with both guns after installing the Agency Arms trigger, racking the slide become a little bit more difficult, no idea why.
After the range today when I was checking the gun at home and I've noticed that the locking block pin is not fully seated, most probably I wasn't paying attention when I was switching the triggers, not sure if this can cause such malfunctions.

The only I can say is put the OEM trigger back in and try again. As with troubleshooting anything go back one step and try and isolate the problem.

First of all, nobody knows what the fuck an FTF is.  

FTFire or FTFeed?

Second, undo whatever you did and it’ll work.  

Don’t use junk mags.

I'm planning to do this during the weekend and I'll check how it will perform. In the meantime, I've tried to replicate the issue with snap caps and it looks like the round is getting stuck under the firing pin, this is exactly how it looks: https://www.reddit.com/r/Glocks/comments/f1s7wm/glock_43_failure_to_feed_caused_by_firing_pin/