I would like to ask some advice and suggestions for mounting a Red Dot sight on my bull barreled, Mk II, 22 LR pistol. Because of aging eyes I have decided to mount a Red dot on my pistol and have already had my gunsmith drill. tap, and mount a picatinny rail on my barrel. My question is now, what is the best Red Dot Sighting system I can mount on my Ruger Mk II for 5 to 20 meter bullseye shooting. Some many types out there, it's confusing on dot size, shape, etc. Help please?