[gbarber010]

I just bought a Glock 27 Gen 4 and have put about 125 rounds down range. In the last 50 rounds I have had a few failure to return to battery. They started in the last 3 mags shot. A few days ago, I shot about 25 rounds with 1 FTRTB or FTF in the 2nd to last mag.
When this has occurred it seems to be about 3/4 ways out of battery. All I need to do to get back in action is to pull back on the slide and release and all is fine. It has occurred with Federal Champion (a few times), Federal HST (1 time) and Tula Ammo (1 time in that 25 round session).
One observation I have is my 3 mags have strong springs and the 9th round is a bear to get in. This has not occurred after the first round fired from a mag.
Thanks in advance for any responses and I hope I have given enough infomation.

[JR]

I would chalk this up to a break in issue. The new mags are feeding the rounds as well as can be expected. Worse case, the feed ramp will need polished.

[gbarber010]

Thanks for the reply. I went by the shop where I purchased the 27 from, and they advised to check the mags. I went out and fired 30 rounds and the problem continued with all three mags. This time, I inspected the weapon more closely during the problem and discovered that my slide catch was popping up during recoil and locking the slide back. That reminded me that I had an extended slide catch installed right before the problem started. I went back to that shop and they replaced the extended slide catch with a new one. I then went to my dept's range and fired 52 round through my 3 mags. All rounds ran flawless. The extended slide catch was a glock part. I assume the spring on the first one did not apply enough pressure to keep the recoil from causing it to catch. I'll have to keep and eye on this, but I think the old slide catch was the culprit.

[JR]

I guarantee it was installed incorrectly. Dont throw it away, simply re-install it (correctly)