... I am comfortable shooting 45 cal., 357 Magunum , 357sig,,& 9mm. With thee exception of the 357 sig my accuracy is very good---the 357 sig my accuracy is excellent. ...
Not really being able to know what you mean by "comfortable", I'd have no way of knowing your skill and experience in using any of the listed calibers in static, comfortable slow-fire target conditions, let alone in dynamic, fast-paced, rapidly evolving and chaotic shooting situations that might occur in an actual shooting incident.
Have you taken all 4 of your preferred calibers to any IDPA events, trying your specific guns & holsters under the self-induced stress of competition? That may tell you something that shooting them on a leisure/target range might not. Just a thought.
I've carried issued handguns chambered in .357 Mag, 9mm, .40 S&W and .45 ACP. (Those, and other, calibers as personally-owned weapons, too . Never carried a .357SIG because it wasn't issued, and the ammo availability in my area is less than ideal, so I've never felt like buying a gun chambered in it.)
I'm less interested in specific calibers for any sort of "stopping power" or attributed "caliber-based effectiveness", than I am in their other potential caliber-based influences, such as controllability and recoil management. Some folks can better shoot some calibers than others, especially under severe stress.
Suit yourself, for the reasons that make the most sense to you, and allow you to make the most effective use of your skills. (Further skillset development and recurrent training is generally a good idea, too.
)
It's just a handgun.
FWIW, since I train quite a bit with 9, .40 & .45 (and other calibers)... when it came time to go get a new issued weapon, which was available in all 3 of those calibers, I told the guy running the inventory to just give me whatever worked best with how he wanted to manage his remaining inventory/availability of the new guns.
He handed me one chambered in .40 S&W (M&P40). As a member of the firearms training unit & an armorer (retired, but current reserve capacity), I could've asked for, and received, anything I wanted (he offered). Or, I could've carried any one of several of my own guns that were on the current approved list (or bought yet another one). The M&P9/45's are apparently in high demand, so I gladly took the M&P40.
I'm less concerned about caliber, for the sake of caliber, than I am about being able to accurately, controllably and effectively
run the gun, especially in demanding and stressful conditions.
Suit yourself.
