Buying new pistol, need advice

[PARAGON]

In magnum centerfire rifles, the casing is generally longer AND "fatter" than their non-magnum counterparts.

It's a design element. In theory, one could design a "magnum" cartridge that was the same height as it's standard counterpart, but with a fatter casing and then neck down the top to fit the caliber. That's just not done in handgun applications.

I think that was what you were refering to.