This is a discussion on How do you define "fits my hand"? within the General Firearm Discussion forums, part of the Related Topics category; Here's a decent atttempt complete with pictures: http://www.corneredcat.com/FirstGun/TryOnGun.htm That's exactly what I was trying to describe. Much easier with pictures....
Mine goes kind of like this if i can pick up the gun and it feels like a extension of my hand or fits like my fav gloves that a good start ..
Can i run all the control with my shooting hand with out twisting my grip? One i have a grip can i grab the barrel and easily twist it out of shape .. etc etc
When you pick up a firearm that truly fits your hand...you'll instantly know that it "fits" your hand. At least I know it.
If you're standing there with the firearm "in hand" wondering if it fits your hand "perfectly" - or NOT - Then It Doesn't Fit Your Hand.
End Of Story.
Not sure if you instantly will know if a gun fits. Yes for us old timers to the shooting sports. I find even my HK w/ the extended slide release I need to slightly shift my grip to drop the slide RH'ed. Luckily I am LH and use my index finder to drop the slide on all my semis.
I know of no guns out there small enough for my hands to work the controls w/o some gun shift. I think finding a gun that naturally settles in your hand and you can point with your eyes closed and be close to on target is what you are looking for.
Nemo Me Impune Lacesset
It is kinda like trying on shoes. You feel the fit and know that it is what you have been looking for sofar as comfort and utility are concerned. Then you take it to the range and prove that the fit is correct.