I have tried, it appears, to obtain most every toy known to modern man - boresighters included. The best I have been able to find is the one made by Alpec - nothing is going to beat the time spent at the bench, however this device will save you all kinds of time, and it is fun. I have found myself in the habit of keeping it in my pocket while hunting - just in case something gets bumped in a fall or something. Just a bit of insurance. Good luck