Bought a PSA GEN4 8" 9MM 1/10 GX M-LOK MOE EPT SHOCKWAVE PISTOL without realizing the importance of having the bolt hold open feature. Trying to use the carbine for competition and it’s very cumbersome without this feature. My question is, is there a way to get that one part and install it or do I need an entire receiver. If I need a receiver how do I know which is compatible? Mine uses glock magazines.