Any time you put metal into the end of your barrel is a no-no for me. Personally I do not like the bore sighters, and would not buy one. I also believe they are a waste of money, and most people I have seen over the years who supposedly know how to use them are normally hit or miss.

If I did buy one it would be one of the laser ones , however as I said above I would never put one in the bore of my rifle. Tom.