glock 18c issue

[Daiviet]

I've managed to solve the problem. The magazine catch on my glock is plastic, and it has a lot of wear on it, so its actually quite simple for a little pull and the mag to come out without holding the mag release. combined with the wear and a heavy 49rd mag, the top valve doesnt actually touch the gas chamber, but instead sits like a millimeter or two below it, not cycling the gas properly. I assume i should get a metal mag release.