Push tab down slide on gun. It locked in easy... Don’t know what your moaning about. So here is excellent news. The lasermax 5mW is eye visible with the 1000 lumen Surefire. I only tested the light for the photo but trust my word on it. Arms Unlimited has these free shipping for $192 if you need an X300U on the cheap. They advertise it as 600 lumen but I got the 1000 lumen.