I finally had a chance to shoot my brand new G27 last weekend. This is not my first Glock, and like all my firearms I gave it a cleaning, lube and inspection before taking it out. Just before finishing my first 100 rounds through it, I had a failure to return to battery. It was pretty cold outside, about 27 degrees, the slide was felt stiff but with a push on the slide it returned to battery. It was my first issue with any of my Glocks, and at first I wondered if it was just the cold. I fired it once more, and had the same problem, so I stopped shooting. At home I field stripped it and found that the large spring in the Recoil Spring Assembly had jumped the lip as the rear of the assembly. I was able to snap it back into position with the help of a needle nosed pliers without visibly damaging anything and it looks ok and seems to function ok after assembly. I have dry fired it several times. I have been reading this forum for quite awhile, have done some searches, and not heard this being discussed, so I assume it is unusual. Anyone ever have this happen to them? Are there reliability issues with this type of Recoil Spring Assembly? I have heard that all the Generation 4 Glocks will have this type Recoil Spring Assembly, and this has me thinking that I should wait a good long time to get a Gen 4 and see if others have problems. Would anyone every trust this failed spring to use again? I have already ordered, received and installed a new one from MidwayUSA, because I would like to shoot it again this weekend and I don't trust the one that had failed. BTW, these aren't as cheap as the other style recoil springs, do you think Glock will send me a replacement?