What we normally know as the 9mm AND also the 9mm Luger, 9mm Parabellum, 9mm P, 9mm Nato and 9x19mm are the same round and they are all names for the standard cartridge all commercial semi-auto handguns SMGs and carbines are chambered for.
The 9mm Automatic (or 9mm Auto) was a prototype round that to my knowledge no one has taken on commercially. As you noted it has a straight case, as opposed to the very mild taper the original round has. This straight case is a “feature” of dubious value to this particular round which has been around and working effectively for over 100 years in it’s standard form.
Your 365XL is chambered for standard commercial 9mm ammunition and I can basically guarantee you it will run flawlessly with any quality commercial ammo off the shelf. The 365s I’ve fired have been absolutely reliable and above average accurate as just about all SIGs tend to be.
I think you may be confusing the 9mm Luger, Parabellum et al with the 380 Auto also known as the 9mm Kurtz
The 380 Auto (also 9mm) is a straight walled case (0.373" all the way to the base) while the 9mm Luger is a tapered case (0.391 at the base and 0.380 at the mouth).
That said you can shoot 380 in a 9mm (much like the 38SPL and the 357 Magnum) but it may or may not have enough “ooompff” to operate the gun depending on the platform. There is also a difference in rim diameter 0.374 for 380 and 0.394 in 9mm Luger.
I just tried my buddies XL and it’s a heck of a gun. I think I’m going to get the smaller one only because what I really need is a tiny 9mm for IWBA carry because my wife wants her Glock 43 back. She loves that gun and I keep stealing it for t-shirt/shorts wear. But in reality, as nice as the Glock is I have to work to shoot it as well as I want when runnin’/gunnin’ and that annoys me. The 365s I’ve shot basically make me look good without ANY effort in my part.
Yeah snappy is a good word for it but my issue is that it’s so light and the grip is so tiny it tends to dive nose down on me when I’m working it fast and furious. My Kimber Ultra Raptor is really not much bigger and I shoot it much better, so the 43 only goes out if I’m wearing the most fitted clothing I own. Even under a simple T-shirt I can make my Kimber Ultra Raptor disappear in AIWB carry.
Not at all. Glocks are great firearms so are most 1911s, XDs, S&W revolvers, H&Ks, SIGs And many others. Having one “fit” you better or having a preference even based on aesthetics does not mean any others are “inferior”.
I personally find my 1911s easier to shoot but have no issues carrying other platforms at times. My wife has no preference between her 1911 and her Glock 43. My daughter prefers her Shield and her Kahr and I’ll be buying a SIG 365 soon as a light summer gun option. Whatever works for an individual at any given point is the right choice as long as they are proficient with it.
@TexasEskimo it’s not an us vs them thing but I and a great many 1911 guys have to consciously “push” the muzzle down for each shot with a Glock. I love the reliability of a Glock but it doesn’t fit me well and I’m not willing to invest in the training it would take to the detriment of all the other pistols I shoot just to master it. Hence it gets no love from me. I’m not a “brand” guy, I’ve had Pontiac, Nissan, Ford, Doge, Chevy and Toyota. Same holds true for guns, it’s what works, not the badge.