Wow this is highly coincidental, cause just today I pulled out my universal one and the batteries were all corroded. I was thinking it would be cheaper to by a whole new one, than just get batteries. The universal ones aren't really "bore" sights, as they go in the barrel and not the chamber/bore, but that is just me being picky ;-) My universal worked well, and like others have said, gets you on the paper first shot but still needs to be fine-tuned. If you get the universal, make sure it is sitting in the barrel nicely, as mine would kinda slide forward a bit and not do the job.