I put a scout mount on my .357 Handi, and I liked it. I never did drill and tap the third screw, just loc-tited the other two and it was fine. I finally took it off and put a regular 3-9x50 on it because the little pistol scope wasn't giving my old eyes enough light.
Mine never shot loose with the .357 and I think the .223's light recoil would be fine too.
Pete