The MP5K is the shorter variant of the German MP5 sub machinegun. The "K" in MP5K stands for "kurz", which in German means short. My lego version has a working trigger, working magazine lock, working charging handle, a safety, and accurate iron sights. It took me only two days to finish this. I had to take apart my M4/M16 to build this, but I've had those built for a long time and I really wanted to build this. Enjoy.