Originally Posted by WT
I forgot to mention that the early USP's had a HK specific light rail. Only HK lights would attach to the pistol. Later they changed the light rail design to accept the more commonly available lights made by other manufacturers.
Thought the USPs still had that HK rail. I have a USP .45, not too old judging by the later hangrips, and I had to get a GG&G mount for it.