Let me address the "Why does it have to be a .357 Magnum (specifically a 4" stainless GP100)?"
Because: 1) My 4" stainless GP100(s) (to be used as the 'reference gun' for this entire post) handles bullets, with weights from 95g to 200g, of lead, jacketed, rubber, and plastic. 2) It handles two calibers, 38 Special and .357 Magnum. 3) Proven defense capabilities in a recoil-controllable platform; 110g JHP's to 125g JHP's. 4) Animal defense capabilities, given correct loads, up to bear (no, not best, but capable). 5) Ammo is ubiquitous. 6) As of this moment, ALL GP100's I have owned, tested, made ammo for, or read about, have given fantastic accuracy with at least one load (I mean totally completely unbelievable accuracy!). 7) Inexpensive in all ways; purchase, ammo, service, aftermarket custom parts, etc. 8) Low maintenance.
My personal GP's wear Pachmayr Decelerator grips, and high-visibility Millett orange-ramp front sights. Both have delivered 4" groups at 100 yards. Both can send my 180g JHP hunting load out the barrel at 1160fps +. They can both spit 125g's at 1500fps +.
Manual of arms is easiest with wheels, as is securing safely.
Plus, I like the way they look....
Questions?
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"All my ammo is factory ammo"