Since there's no master switch, you'd have to take them completely off the gun and remove the batteries. I've been using mine on a Glock 26 and a 17 for several months now, no problems with batteries on either gun. I used Lasergrips on a 1911 and a J-frame revolver before I went to the Dark Side. The 1911 had a master switch that I never used. No battery problems. The J-frame "boot grip" style Lasergrips don't have a master switch. No problems there either. Just change the batteries periodically, like you would with an Aimpoint sight, and you should be fine.
As someone else posted, they come with two very small allen wrenches to regulate the sight. It took me about two minutes in my living room to get them roughly sighted in, so that the dot sits on top of the front sight at 7 yards. I made some minor adjustments at the range to get it perfectly dialed in.
As far as usage, these things really do work. I do a lot of movement drills (box drills, snakes, etc.) in my personal training, along with scenarios that somewhat replicate defensive shooting. The dot makes shooting on the move much easier.
I also took a handgun novice out a couple of months ago. By the end of the afternoon, after a little training, he was shooting scenarios VERY effectively using my Lasergripped Glock 17. I mean fast AND accurately. The dot sight really helped him. I know this because, as an experiment, I put a piece of tape over the laser diode and his performance plummeted.
The only issues I've had with these grips:
1. On all the units, when the trigger finger is "in register", it blocks the laser dot. I simply retrained my finger to stay slightly lower so that it clears the dot.
2. When shooting weak-hand only with the Glock units, the laser housing beats up the base joint of my thumb. I'm working on a slightly different grip technique to minimize this.
3. The Glock units do make the gun a little wider. I wear pretty loose clothes most of the time, so it's not an issue for me, but people who wear tighter clothes might have problems with concealment.
Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!