S&W was sued by Glock over the design of the Sigma. S&W ended up having to pay Glock. The SD9 followed the Sigma, and then the SD9VE was produced. They must have changed it enough to get around whatever part of the design that Glock sued for, but I don't know for sure. These days there are a lot of Glock Clones that will interchange with Glock parts. The SD9VE is not one of them.Is this the glock copy gun?