I need your guys help before i send my G27 back to Glock. I clean my Glock after every range session. I just went out behind the house and fired 40 rds. w/o issue however when i went to shoot another mag thru it i had a failure to feed after the 3rd rd. I only load the 9 rd mags to 8 so i could shoot 3 rds fine but the 4th would not feed. I tired several mags with same result. I had this issue a month or so ago and changed recoil springs and it went a little over 100 rds fine. I have no idea what it could be. The gun is clean, not overlubbed. o i have no idea what it could be. I have tried several mags still with same issue although some malfunction more than others. I switched the recoil spring even tried different ammo but still having same issue.

I'm assuming this was a working / reliable pistol a one time? Where is it hanging up? How far is the slide closing and what position is the bullet in? How are your mag springs? Have you detailed stripped either the frame or slide? Do you have a new mag you could try? Is the different ammo you tried all factory? or any reloads? HP, or FMJ? Have you let anyone else shoot the pistol? Is your thumb by chance riding upwards near the slidestop? Have you cleaned the chamber and feed ramp good? How about brushing the breech face and the extractor claw?

I have had it for about 3 months At 1st I had issues with the same FT Feed. I changed recoil springs and it worked fine for close to 100 rds. I have tried different ammo both FMJ and HP. I have used a total of 5 different mags and while some do it more often than others all have at some point hung up. The slide locks back as if the mag was empty. All ammo if factory Federal or Winchester. I have tired both 180gr and 165 gr. and it does it equally with all ammo tried.  I own several Glocks and owned a 27 in the past that was flawless so I don't think it is my technique especially considering if always happens after firing the 3rd rd from a loaded mag. I always clean the feedramps and chamber after every use. I had my brother in law shoot it and he had same issue. I always brush the extractor claw and breech face with a metal cleaning brush after every time shooting it. I am totally lost. Have no idea how to go about polishing feedramps and don't know if i should since it may void warranty.

I'd be willing to bet your thumb is activating the slide stop lever.  This happens with my 27, only when I attempt a thumbs-forward grip.

I had a 'issue' with my G20SF' not feeding the last round.  Inspected the mag and found that the front of it was starting to crack.  Went to a different mag and not problems.  I sent the mag back to Glock and am waiting to hear from them.  I have not had any issues with my G27 and have shot several hundred rounds through it.

That jumped out at me while reading that response. I just went through this issue with another shooter using a 26. They were inadvertently pushing the slide stop up during firing. Has the frame been detail stripped/is the slide stop properly installed? I would suggest shooting it left handed and see what results you get. This would prevent the accidental slide stop activation.

I agree it's likely an case of inadvertantly bumping the slide stop.  This comes up periodically on the forum, especially with newer Glock shooters.

There is no conceivable mechanical reason for that G27 to behave like that.  It's the thumb. Have your thumbs trimmed back about 1/2". Of course, it could be that the slide stop spring isn't installed correctly.

Thanks for all the replies.

I am going to try left handed since I am left handed just switched to right a couple years ago because I am cross eye dominant. Hopefully that will fix it because I can not see anything mechanically wrong with the pistol.

Thanks again guys.

Thanks for all the replies. Just went out and shot 50 rds trouble free. I guess I was the issue as you guys stated. I am left handed but switched to righty a few months back because I am cross eye dominant. I shoot my full size Glocks and 1911s better right handed but I guess my thumb was hitting the slide lock lever or I was limp wristing with my weak hand  because it functioned fine left handed. Thanks again.

Glad to hear everything is good to go!