Recoil turns laser off - Steiner TOR Mini Laser Sight

Have mounted on a glock 21, I have night sights on it, so I didn’t want a flashlight to blind out the sights. Figured a laser would be a good option, and I opted to buy a higher end one (this one). Bad mistake. I can get sometimes 3 or 4 shots off, sometimes a full magazine, but the laser always turns off as I’m shooting it. Sometimes the recoil turns the laser off, sometimes I can’t get it to turn back on unless I put a new battery in it. I’ve taken it to the range twice. Just get something cheaper.