I bought a KWA USPc a time ago from another AS member. And the gun locks back after every shot. And with gas guns sometimes its hard to tell whats actually wrong with it. So in order to make it not do so I hold down the slide release lever with my thumb while shooting. I don't know if it's the slide release lever or something else. I've tried cleaning it and putting some silicone around general areas. But it still continues to lock back. Any suggestions?