UPDATE: TO be fair, I decided to update this review after messing with this device for awhile. I disassembled the machine and test fitted the bore sight in the barrel. It did fit. I replaced the barrel without using the spring and was able to get the bore sight to chamber correctly. I am concerned that it doesn't seem to work well with the extractor, but if you do push the slide, it will seat. I was actually able to use it with the Hellcat to check the bore sight. It does work, but again, a little nervous about the edges fitting into the extractor pin. I will try it again on other brands to see how it does. Score increased.
FIRST REVIEW:This will not chamber correctly and when your barrel does not go into battery, it renders this device completely ineffective. It is of absolutely no value whatsoever! This junk should not even be sold on Amazon. I believe most people that buy this probably use it to entertain their cats, not sight their 9mm.