Just a little clarification. The money charged for installing sights was refunded to mister "Einstein" to make sure we are not seeing him again in a shop. He started to yell from the first minute he entered the shop. Apparently he is not a big shooter, that`s why he decided to install more complicated night sight set, that were installed and collimated to zero point. He never shot the gun either, however he loosened the set screw that was holding the sight, that`s why the sight fell off . Anyways, we did not want to discuss any further with him nor we wanted to reinstall those sights back because of customer attitude we just paid his money back, without any wishes to listen his high toned complaints for damages not caused by us .