I bought a .223 boresight laser from cabelas. I have a M&P 15. It will not work. but works good in a 12 gauge?
Any way the 12 gauge sleeve works great, so its not the laser.
So just use it in your 12 gauge and use slugs instead of shot. Or, since you need to sight it in, check the reviews on the item and if they are good, yours may be defective; I would ask for a replacement or refund. If the reviews are not very good just get a refund, and do some good old sighting in.
Laser Bore Sighting a Red Dot Sight