I know this has been asked here before and I have gone through many of the old threads, but I was unable to find a relatively affordable way to mount a red dot sight. My question is has anyone here ever used a rail adapter and a standard pica tinny scope mount on a USP. Specifically a USP .45. I don't know if the sight would hold a zero if you did this since it would be attached to an adapter and not the actual rail. The reason I am wanting to do this is so my father can try out a red dot sight without milling the slide or removing the sights. I have found the ones made by HK, but don't really want to spend $200+ on a mount when you can buy them for pica tinny railed pistols for $50. Any help would be greatly appreciated.