establishing the fit

[ericf]

With the newer generations of auto's, they all seem to have the interchangeable backstraps for a better hand "fit". But no where can I find a description of what that "hand fit" should be.
Should the grip size be based on comfort? Hand wrap around the grip? Finger length?

Just how should one judge the proper grip size in order to utilize the correct backstrap?

The small feels right, the Medium feels right, the large, I can get used to (ala Glock 17 gen3).
I'm currently enjoying the M&P 9 Pro.
Thanks for he help.

[JV_]

This may offer a few tidbits for you:
http://pistol-forum.com/showthread.p...of-a-good-grip

[ToddG]

1. Choose the panel(s) that gives you the best access to all controls -- trigger, mag release, slide release, safety, decocker -- without compromising the way you want to manipulate the gun.
2. If multiple configurations meet the requirement of #1 above, choose the panel(s) that turn in the best accuracy and speed as you shoot. For many people, this will be a bigger grip than feels most comfortable.

[scothill]

I just put the different ones on and ran the gun doing varous drills and slow fire accuracy. After that it was pretty clear to me, which one fit me best, and it actually wasn't the one that felt the best. In my experience there was a noticeable difference in how naturally the sights lined up, now easy a correct trigger pull was, access to controls, etc... However, in my first Vickers class I ran medium and in the second large and did fine with both. I liked the medium for feel and ended up running the large on my M&P9s. On the 45, I am still bouncing back and forth between the medium and large, but it is kind of moot as I am running a 1911 this year.

[JV_]

and it actually wasn't the one that felt the best.

IME - That's pretty common.

[Kyle Reese]

Having used all 3 of the M&P backstraps, I have found that the Large is the most comfortable, but I shoot best with the Medium.

As a result, the Medium is on, and will stay on, all of my M&P 9's.

[jetfire]

I ended up going with the large in my M&P Pro Series .40 S&W. I could "cheat" with the 9mm, but with the .40 the extra snap of recoil forced me to pay more attention to my grip. I put the large backstrap in because it gave me more contact area between my support hand and the gun.

[JHC]

1. If multiple configurations meet the requirement of #1 above, choose the panel(s) that turn in the best accuracy and speed as you shoot. For many people, this will be a bigger grip than feels most comfortable.

THAT was a big shocker to me but proved true with the M&P Pro9 I had an my Gen 4 Glocks. In the case of the Gen 4 Glocks, with the large backstrap, I get TIGER level slide bite however. ("You'll fight TIGERS!")
I think it moves my hand just that much higher, which I like, except for the incessant bleeding. And pain. LOL

[jslaker]

IME - That's pretty common.

This is why I tell people to rent/borrow the guns they may be interested in and actually shoot them. Fondling them in the gun store doesn't really tell you much more than how it feels, which can by misleading.

[YVK]

but it is kind of moot as I am running a 1911 this year.

To me,1911 is a first pistol with interchangeable "panels" and "inserts" and most of my experimentation in regards to fit comes from 1911. Between different shape mainspring housings, regular vs. slim bushings and grips, and trigger lengths, you can get a lot of variability.
That said, I try to go for a slimmest, narrowest profile possible as long as it is not uncomfortable or impeding to manipulations. I've not found a lot of difference in performance between different profiles when shooting two-handed. With one-handed shooting I can control pistol a lot better if grip is slim. We can argue how important it is to shoot well one-handed on a big scheme of thing, but, since I, and for that matter most people I've seen, don't look too hot on one handed drills, I find this a welcome benefit of slimmer grips.