Hfc m9
 

This GBB is having some cycling issues, but I'm not sure why.

With its stock HFC magazine, it seems to work fine when cycling, loading, and shooting. However the slide doesn't go far enough back when shooting, for it to lock when the mag is empty.

The the unknown brand of m9 magazine, the gun doesn't work at all. When you rack the slide, and shoot, its fine, but it fails to chamber another bb after the cycle, but it seems this is because the slide isn't going far back enough, again.

So its looking like a cycling issue, but I could be wrong
I've never particularly worked on pistols, so as to why this is happening, I'm not even sure. Would there be any particular reason as to why the slide isn't blowing back far enough?
Help would be appreciated.