Review on Accurately Sight In Your Shotgun With The Sightmark Red Laser Boresight by Vladimir Castillo

Just what is needed. I put in the wife's 20g and it showed exactly where the gun was pointing so she could practice bringing up the gun and seeing where she was aiming. The original batteries that came with it had one bad one but once I got that sorted, the signal (reg light) was just fine at 30 yards into the trees when it was not bright sunlight. Since there is no "on"/"off" switch, just put a small piece of paper between the last battery and the cap so you store the batteries in the unit without it being on. Be sure to carefully/softly close the action to hold the laser firmly in place - if you don't, it will wiggle a bit and not be nearly as accurate. I don't know how these will do out at 100 yds. but we don't shoot birds out that far so it was not an issue.