Bore Sighter that works with these/any airguns??

Since it's wintertime in Montana, it's difficult to get a day that allows for outdoor shooting.... and my space indoors (my shop) is maxed out at about 40 ft. I've just purchased 3 new guns, (Niksan Ozark-TS which you will hear about in another thread, a Gen2 Barra 1100z, and a Umerex Notos) and would like to get them at least boresighter/close while I wait for decent shooting weather.

So, this leads to the question: Which/what Bore sighting device will work with these airguns? I've already tried the "laser bore sighter" which isn't long enough to reach any of the barrels of these guns (its getting returned). At one time I had an old Bushnell bore sighter....the one with the grid pattern, and interchangeable adapters, that worked on both a Maurader and Gauntlet 2.... but I have misplaced that device, and before I plunk down the money for a new one...... it's be nice to know if it will work on the guns I've mentioned??

Thanks in advance for advice/help!
 
I have one of these that works on barrels, if you have a non magnetic shroud it won’t work but I have used a 1/2 x20 nut to thread it on guns that have threaded shrouds. It gets me on paper.

IMG_0333.png
 
I have one of these that works on barrels, if you have a non magnetic shroud it won’t work but I have used a 1/2 x20 nut to thread it on guns that have threaded shrouds. It gets me on paper.

View attachment 533881
I have one that looks like that from Caldwell. End with the rings attaches to muzzle end magnetically. If you do not get it centered on the bore it will introduce some parallex, either vertically or horizontally or both, depending on position, but still will get you close onto target.. Biggest variable will be if the muzzel is square to the bore axis.
 
Shoot 3 to 5 shots from 10 feet to see if the cluster of holes in the target are about the slight height below the line of sight. As in 1.5 to 3 inches, depending on rifle or bullpup with tall sights. Adjust for horizontal offset and shoot another cluster. More importantly, do the pellets land on your trap at that distance?

You can adjust the sights to null out the vertical offset, but as soon as you move to 20, 30 and 40 feet you will need to undo the offset required to superimpose the POI on the POA. Wait until you are at 40 feet before you make your final precision adjustment. Even then, depending on sight above bore height you probably need to re-zero for 25 or 50 yards, if that is the range you eventually plan to shoot at.

As for a bore sighter; if you don't have one, you don't need it. Just start shooting at a distance so close that you could hit within 2" of the bull, even without any sights on the airgun. Then make sensible adjustments as you move further away in 10 to 15 foot increments.

You can leave your mufflers on with the very simple technique above.