WE Hi capa 5.1 r-type slide lock
 

Most of the time when I insert a new mag into my hi capa with the slide locked back, nothing happens, I have to manually hit the slide release to chamber a BB. The odd 3/10 times or so my slide will slam forward by itself. My KSC USP's slide goes forward with a new mag 100% of the time and I was under the impression that hicapas would do the same. Anyone knows what's wrong?

I'm sure that the slide is not suppose to be going into battery when a fresh mag is inserted. Your KSC slide catch could be worn and just a slight hit when a mag is inserted cause it to go into battery. Nothing to be concerned about.

This, +1.

Well with mine, it just depends how hard I insert the mag.

"Slaming" it (gently) will unlock the slide.

But I never do it, I prefer hitting the slide catch.