The Star Z-63 is a 9x19mm version of the Star Z-62, which was made in both 9x19 and 9x23. Together, these represent the company’s effort to produce a more modern submachine gun than their Z-45, which was basically a copy of the German MP-40. The Z-63 is, contrary to its external appearance, a well built gun with several clever internal safety mechanisms. It uses a spring loaded firing pin which only protrudes when the bolt is fully closed, and also has a lock on the bolt that prevent it from moving rearward unless either fired or cycled using the charging handle. This prevents potential accidental discharge if the gun is dropped.