G21 problems...

[ed]

I've owned my G21 for ~4months (1st time Glock owner).  I've put about 300 rds. through it, all 230gr. FMJ's.  Every once in a while, regardless of the magazine or number of rounds left in it, the slide locks open in the middle of my shooting.  The gun isn't jammed, no empty in the chamber, the slide is just locked back as if I had locked it back myself.  All I have to do is hit the slide release (or pull back slightly on the slide) to chamber the next round, and I'm good to go again.

I've payed great attention to my thumb, making sure I wasn't touching the slide release during shooting.  Other people firing it have the same problem.

I've checked the slide release spring against a G22, and can't tell much difference in tension.

Anyone have any suggestions?

[JeffG]

Can you locate a Glock armorer to look at it?  If you can be sure that the gunsmith you bring it to is GLOCK CERTIFIED, I would do that.  I think something has a burr on it somewhere.  Good Shooting.

[Savage]

Ed,
I bet the problem is in the assembly of the slide lock. The spring is not properly positioned under the top assembly pin. This causes the slide release to bounce up under recoil and catch the slide. The upper leg of the spring has to go UNDER the upper assembly pin. To fix it remove the slide and take a drift punch or like tool and push the TRIGGER pin out from left to right----not all the way but enough to release the mag catch. Remove the mag catch and reinstall it on the trigger pin with the leg of the spring under the top assembly pin, pushing the trigger pin back in place. Reinstall the slide and fire away! If you are not familar with the complete disassembly of the Glock get a book or go online and you'll find all the info you need to do most anything to a Glock. These things are even simpler than a 1911! Complete disassembly and assembly with only a punch (except for the mag release) in under 5 min.
Love the 21!
Stay Safe,
Savage