As many have come to realize upon installation of metal upper and lower receivers on the (WA) Western Arms M4 GBBs, the pins become very loose with none more so than the front locking pin. With this in mind G&P has released this very useful front lock pin (commonly called the Magic Pin). Cut from steel, this front lock pin features a hex screw which holds this 2-piece pin in place, firmly securing the upper and lower receivers together. As you screw it tighter, the pin expands and fills any space in the hole to create a super tight fit, and eliminate any wobble for a firm feel!