I used to have a cheap BSA red dot on a Ruger MK III, 22/45. A bit big and top heavy, but man that thing would shoot. I just used the mount that came with the gun (already drilled and tapped).
I highly recomend it.
For God so loved the world, that He gave His only begotten Son, that whoever believes in Him should not perish, but have everlasting life.
John 3:16 (NKJV)