I reckon I question those "theories" .... counter to what I learned as a youngin'. Being a Cooper fan, I've had my .45ACP Combat Commander (steel) for over 40 years .... back then, that round was touted as having 95% of the stopping power of a .44 mag, but in a realistic defensive spoon.
I've had the revolver hand canons forever too.... they just aren't fun to shoot with magnum loads to me..... so my goto was the Colt for decades. But I'd hate to part with any of my old Colts or Smiths, so they became safe queens. The baby Ruger LC9S is my pocket spoon (living in my truck toolbox), and for home defense I opt for 00 defensive load buckshot out of a Remington pump, or my Marlin .357 lever.... I gots 4 legged predators too ;). Anything I grab is more than potent for any threat... and Jeff Cooper taught me well 5 decades ago :D.

The 6.5 is flat shooting and is very accurate at long range.

The 6.5 x 54 was used to great effect by the Ivory hunters in Africa in the early 20th century.

The Swedes used the 6.5 x 55 as their military round for apx 70 years..1896 through the 60's. The 96 and 38 Mauser's are very popular milsurp rifles.

Long range is relative I suppose .... due to hilly terrain here and woods, most shots are short, and 100 yds would be "way on out there"... nothing even my magnum Smiths couldn't reach if necessary.
My uncle sights his rifles for reaching out to 500 yds, but that's for out west, Alaska, and Canada.... unheard of in these parts.

Hence my old .30-30 is a long range spoon :D

If you are talking feeding issues, I thought the issue was the feed ramp on the upper.

I've seen way too many calibers come and go over the course of my shooting career. I'm leery of buying anything that appears to me to be the "next big thing" because, well, every damn one of them that has been introduced during my lifetime has petered out. .357 Sig, .40 S&W, 10mm Auto, .32 H&R Magnum, and a few other handgun calibers come to mind. And look at all of those Winchester Short Magnum rifle rounds - all but gone and forgotten. Next up will be all of these new introductions from Nosler - I'll bet they are gone and forgotten in less than a decade.

I like my "using" calibers to be pretty mainstream. .38 Special, .357 Magnum, .44 Special, .44 Magnum, .45 Colt, .45 ACP for handguns. .223, 6.5x55, .30-'06, .375 H&H, .45-70, .458 Winchester Magnum for rifles. I know when I'm traveling to hunt, should my ammo get somehow separated, I can find these locally.

Of course, I do like the obsolete and weird, you guys know that. But I understand and fully accept the fact that those are handloading only, if not bullet casting only options. Those are just "fun guns", for range, match, and plinking use. When I hunt with them, I'm not traveling, so ammo logistics are never a thing.

Unfortunately, the shine has kind of worn off of the .40 S&W. It's neither fish nor fowl. It's a compromise that made sense at the time, but with modern ammo developments, it just cuts too fine of a line between the 9mm and .45 ACP. Much like the .41 Mag, there is no gun specifically tailored to its size and, even if there was, it would be so damn close to a small .45 ACP or a large 9mm that it just wouldn't matter.

Shooters who really like this caliber would be well advised to start saving their brass and learning to handload.

Well, for now ammo is plentiful. I think .40 had more market penetration than .357 Sig or 10mm, so I don't think the ammo will become as scarce. Time will tell.....

Do you know where I can get primers? I only have 1000 rds. :(

I'm seeing them pretty regularly on both Midway and Brownell's websites. I've purchased at least half a dozen bricks of various primers in the last couple of months. I'm not even watching all that close, I only check when I think about it. Just ping both sites once or twice a week and you'll be surprised how often they show up.

I have one of the best 22H collections in the world..and it's only 7 pieces..its not how many it's what..

I bet you have 7 NIB 22H all with serial #00000001.

WTF is 22H ;)?

I had no idea that S&W .40 was getting unpopular. I haven't tried to buy any ammo in a while and almost never shoot my guns, unfortunately. I have enough for one good battle here at the ranch, between 12G/.40/.38 Special/.32 ACP and a baseball bat somewhere if they all run out. :)

If I was a regular target shooter, I'd be more concerned. 10mm I knew was pretty obsolete, I remember when it was somewhat popular when I bought my first Glock back in about 1992. I've never heard about that caliber since.