Ebay laser Bore sights
I usually get good stuff from ebay merchants. But lately there is a batch of laser bore sights that just don't work very long. I have purchased 3 of them and all three died in just a few uses. I bought all 3 from different merchants. One of the merchants I have traded with for several years.
These bore sights have an painted aluminum housing and fit in the chamber of your weapon.
It's a shame they don't last very long, they are accurate.