When shooting a different pistol, I have typically spent a fair amount of effort to reliably acquire the dot support hand only. Since a number of the pistols I shoot in competition don't have BUIS, have different height over bore of the optic, and have different grip angles, this shouldn't be a surprise. The other day, I started experimenting to see if there might be a method, that would allow me to easily move from pistol to pistol, and reliably find the dot support hand only, including from weird positions.
What I didn't want, is a method that relies on using BUIS, focusing on the optic housing, or referencing a stripe marked on the optic. What I did want is a method that allows me to look at a spot on the target, extend my arm, and have the dot appear on the desired aiming spot. What I figured out, is if I look at a spot on the target, extend my arm, with the pistol, and visualize placing the lens of the optic between my dominant eye and the spot on the target, the dot reliably appears on the spot. Keeping the pistol and optic more vertical than canted also helps me.
I have tested this with a number of people in the last day or so, and it seems to show promise, so I wanted to pass it along and see if it is helpful. YVK pulled three different pistols out last night to try, and at the LGS folks tried a FN 509 and a 2011 Open gun.