FTF or FTRTB on a G-27 Gen 4

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.