You make a lot of good points, but again, I can't really justify a .357Mag because my 10mm gets everything done that a .357 would.
I don't agree at all. Before I say why, let it be known that I own one .357 Mag and I own two different 10mm pistols. I've had 10mm since 1994, so I'm not new to this caliber. My carry gun is a G29. I've always loved the 10mm.
With a .357, you've got a completely different type of handgun from anything that you have. A revolver, something that your G20 is not. So that's one thing that your 10mm can't get done that a .357 can.
A .357 revolver uses the horribly plentiful and cheap .357 Mag and .38 Special brass, a 10mm uses the scarce and expensive 10mm brass... AND a 10mm chucks that brass. And a Glock 10mm "smilies" a lot of that brass. As a reloader, you must be cognizant of that.
If you aren't reloading, or stop reloading, or if you are simply out of ammo and away from your bench or out of components, a .357 Magnum is one of the single most popular handgun calibers in the history of the world. Throw .38 Special in there as well, and you've got dozens upon dozens of factory ammo choices from EVERY ammo maker, in multiple bullet weights and styles and loadings. In 10mm, I could almost list all your choices on one of my hands. Granted... this isn't something that deters me at all (I'm a dedicated reloader) but if you want to make the argument that the 10mm covers everything the .357 is, well, wrong again.
As I detailed, a .357 Mag revolver can use incredibly light loads like the .38 wadcutters. Easy and cheap to handload, more inherently accurate than any 10mm load from just about any platform. That's something your G20 can't do. (In fact, I've read from many folks who own both the G20 and the G29 and many state that their 29 is MORE accurate!)
A .357 Mag revolver makes great use of cast lead bullets, something your Glock can't/won't/shouldn't do. Cast lead bullets are the cheapest projectiles you can buy for reloading, and the only way to get cheaper bullets is to cast them yourself. Either way, you end up with cast lead bullets. Another thing your G20 can't do. (of course, with an aftermarket barrel, your G20 can do them, and quite well, too)
Hey, really, if a revolver is not for you, fine. I can't make you get one. If you don't want one, you just don't want one. It's not like I'm trying to sell you mine and I don't work for S&W.
But the reason you state can't really be the reason you believe...
Otherwise, why on earth would you still own the G22? What does a .40 S&W give you that the 10mm doesn't do? The G20 has a 15 round magazine... another mag handy and that's 30 shots, so what is the reason you can justify a .40 S&W if you already have a 10mm?
I'm sure there are plenty of guys who are turned off by revolvers. I'll bet some guys have no use for them whatsoever in their early years of shooting, and gravitate toward them later. A lot of people probably find them antiquated or ugly or low-tech.
If you don't want one, that's all good. But IMO, your reason is just full of holes. And if it all just simply comes down to muzzle energy, and that is what drives your argument that the 10mm handles anything/everything a .357 can do, then instead of a .357, might I suggest a .44 Magnum?
The .44 Magnum will do more than a 10mm in energy. More in bullet weight. Use a similar bullet weight and you've got more muzzle velocity. And every other reason I detailed in defense of the .357 can be applied to a good .44 Magnum as well. Ammo choices, component bullet choices, brass availability and not having to chase down chucked brass.
Anyhow... I've got a couple different guns that don't do "anything" that I can't do with another one. I've got a Ruger Blackhawk in .30 Carbine. Can't do anything with that one except a colossal fireball, a horrendous crack & boom, a flat, speedy as hell bullet and an accurate revolver from which it screams out of. Heh... not a lot of purpose for that one, but I sure like it!
Anyhow, that's my argument. I love all my guns in all their calibers... but if I were only allowed to have one, I'd have to make it a .357 Magnum, for all the reasons I stated. The versatility and functionality of it is unmatched, IMO.