First let me say I know there are 100 different ways to skin a cat if you feel like you know it all please feel free to quit reading and back click now..........When I first got my thermal scope I looked up "how to zero a thermal scope" Found everything from hand warmers to tin foil cut into 2"x 2" squares I tried those, but they don't seem very precise and tinfoil doesn't work very well unless the sun is hitting it pretty good. I wanted to share the method I found and use and it works really well. I use a foam board, some 3"-4" decking screws, white poster board paper, some little white stickys for repairing used bullet holes and a small hand torch for heating the screw heads. Also a shooting vise helps.
What I do is staple the poster board over the foam board set it up at the distance I am going to zero the scope at (36yds for me) put one screw in the center just enough to keep in foam board and about 2.5"-3" sticking out, heat the head of the screw up (rifle should already be set up and ready to shoot) when looking through thermal scope the hot screw head will give a very precise aiming point. Take a very careful precise shot, go back to target and put a second screw in the bullet hole you just made (hopefully your at-least on the paper 2ft x 2ft) now heat both screw heads up. You now have two precise hot points when you look through the thermal scope. Now depending on your thermal scope you can now match your POA to your POI. For me I have a FLIR PTS 536 with the remote so I was able to very carefully position the rifle in my adjustable rest put the reticle on my original POA and with the remote move the reticle to match the POI next shot I took I hit the screw head. I have found this is the easiest most precise way to zero a thermal scope and it can be done in two shots.
What I do is staple the poster board over the foam board set it up at the distance I am going to zero the scope at (36yds for me) put one screw in the center just enough to keep in foam board and about 2.5"-3" sticking out, heat the head of the screw up (rifle should already be set up and ready to shoot) when looking through thermal scope the hot screw head will give a very precise aiming point. Take a very careful precise shot, go back to target and put a second screw in the bullet hole you just made (hopefully your at-least on the paper 2ft x 2ft) now heat both screw heads up. You now have two precise hot points when you look through the thermal scope. Now depending on your thermal scope you can now match your POA to your POI. For me I have a FLIR PTS 536 with the remote so I was able to very carefully position the rifle in my adjustable rest put the reticle on my original POA and with the remote move the reticle to match the POI next shot I took I hit the screw head. I have found this is the easiest most precise way to zero a thermal scope and it can be done in two shots.