JP GMR-13 Double Feed

[Old3GNR]

My JP is now 5 years old and I've run 14000 rounds through it shooting USPSA.  Recently I've had some double feed issues where a round has been chambered but another round has been released by the mag and I get  a jam.  I'm running Glock 31 round mags with Taylor Freelance +10 extensions.  I replaced the mag springs last winter.  Any ideas on whats wrong? 

[egd5]

Are the lips of the mag worn down just enough to let another round sit just a little too high? and maybe just the variance in diameter of the casings let a slightly undersized one slip upward that tiny amount.

[Kokeman]

Try a new mag and see if still does it. 

[TRUBL]

If it is a TRUE double feed....the magazine is junk, and it should not even be holding rounds in when you fill it.......that being said, I suspect you have a different issue.

[Bowman]

Have you replaced your extractor? Sometimes extractor problems can lead to double feeds.

[Old3GNR]

I had previously replaced the extractor @ about 5000 rounds.  I just replaced the extractor and firing pin again.  I did determine that one of my mags has slightly wider lips , unfortunately I don't know which mag I was using when i had the problem.  The gun has been very reliable with only 2 failures,  of course the failures occurred in matches.