I don't know.
Here are my thoughts on it, I don't get it.
I can't justify extending a compact gun, I'd just get a full size gun if I wanted that long of a grip. The grip is the only part that's tough to conceal, you could easily have a 10" barrel but a short grip and conceal it no problem. So you've sacrificed sight radius and muzzle velocity for concealment and then removed the concealment advantage .
Seriously , I'm not knocking you I just don't understand when folks do this. I need to mention, your pinky does not need someplace to rest, it adds almost nothing to grip strength. I think its psychological for people , they don't like having their pinky floating in the breeze .
I keep my carry guns as short in the grip as I can get, a g30 with a 9 round mag leaves me nowhere to put my little pinky yet I can shoot a g30 as well or better than a g21. For me it's normal, my first 3 handguns were SAA clones and they're meant for a pinky curled under the grip.
This same apply to the g19x, it's totally backwards with a long trip but short barrel. A friend that has one said it's so you can clear the holster quicker, I think not.
So I do want to ask, why?
If it's your only gun and you want to increase capacity, I get it. But it's not like anyone buys a tiny gun as a range toy. Help me understand.
How you like that Mossberg?