Just like the title, what does the magazine catch plate do? I'm talking about the black plastic plate that you put in that silver block that sits on the outer barrel. I just noticed my BAR-10 doesn't have this and my magazine needs to be pressed in to feed well and I need to press my magazine release button REALLY hard and deep to fit, so I wondered if this was the problem. If this isn't the problem, what can I do to fix this? Thanks!