The mount fit perfectly and snug! I had to push firmly with thumb pressure to get to slide in, but it didn’t require brute force or anything, nor did I need to tap it in with a punch. No sanding or file, etc. just a slip fit. Likewise, the Holosun fit perfectly. It looks good too. Shipping was fast, and the LEO discount made it a great deal. The only recommendation I could make, would be to off the proper size punch to remove the Ruger rear sight pin. I think I used the shaft from an old broken drill bit. Good luck.