Originally Posted by DFence
Run 9 rounds in the mag and see if they all function the gun. Might be to much pressure pushing up on the 2nd round with 10 loaded.
Some Glock mags require some break in. Also leave your mags loaded for a while and it will weaken the springs a bit.
That's what I'm thinking. My mags are filled with HD ammo (8 per mag just in case)