i grabbed one of these because i found one for well below retail price NIB, and after about 200 rounds on my g22 i'm far less than pleased with the results but not completely. i tried it out in a couple of different setups. first i zeroed it in at 25 yds using a gun vice. took 3-5 shots, adjusted to the center of the group and it was in fact zeroed in for subsequent hand-held fire. next, i used a combination of gun vice, live [mounted] fire and a bore sighter to run the beam parallel to the bullet path. measured the deviation at .3 yds (bore), 25 yds (bore & live) and 100 yds (bore & live) and managed to get it spot on. the first thing i noticed when testing out both setups is that the device does not work in temperatures around and below freezing (32F -/+). well it does, but it's exceedingly faint and flickers in a manner resembling low power. essentially worthless at that point. the next consistent problem i found was laser deviation after firing. both with the quick release securing bar and the tactical securing bar, the laser would deviate permanently to the right after a minimal number of rounds (30-50). the deviation was about 0.75-1in to the right when measured at 5 yds so i didn't even bother to measure at longer ranges. it could be my particular device, the device 'settling' into the gun's rail mount or the internal housing for the laser causing the problem. at any rate, it was consistent enough for me to not trust it. it was pretty easy to conceal and carry just tucked into my belt (don't have a holster to fit the beast) but there is no way of telling if you triggered one of the on-switches while stashing it and wasting away 10 min of a 4+ hour battery life. i think it may be practical in a home sd scenario just by sighting it in with your irons within the boundaries of your living space, and stashing it on a night stand and that's about it.