My thoughts on two cartridges as it relates to this thread:
9mm
I never cared for it... mostly because I read a lot of Jeff Cooper in the 1980s and Cooper had me believing that it was a good-for-nothing cartridge. Now, he may never have actually said any such thing, but Cooper was known for using handguns as fighting tools and/or training for fighting tools, thus, the 9mm had no practical use for him. And in the 1980s, the 9mm wasn't a very good fighting caliber.
Since then, the 9mm has become a better fighting caliber, with bullet, propellant and ammunition technology advances. Still, I don't use it often in a defensive role.
However... I did quit
disliking the cartridge some time ago for a couple simple reasons.
As a handloader... I find the 9mm to be a great cartridge because components are easy to get, inexpensive, and it's an easy cartridge to load very good ammo with. Brass in particular is so plentiful, I have such a ridiculous stock of it that I never need to worry about how much of it I lose in any given range session. And component bullets are a full HALF the weight of .45 cal bullets, which gives me more bullets for my purchasing dollar. Also, when having fun blasting things on the range (I do a lot of that), it's a riot having 15-17 shots before reloading and with the 9mm, you can do that easily.
So though I never cared for the 9mm in my formative years, I have really grown to like it. And to
really get myself to like it even more, I finally bought myself an accurate 9mm, which is a heckuva lot more fun than the simple "combat accurate" 9s that I had been playing with. If you look at all the 9mm-chambered pistols in all the world, you'll find that 95% of them (more?) aren't highly accurate pistols. They might be quality, durable, decent pistols... but they aren't bullseye shooters. If you put some more towards an
accurate one, you might find that the 9mm is a heckuva lot of fun to own and shoot.
.40 Smith & Wesson
...is a round that I didn't particularly care for when it hit the scene and to this day, I still don't care for it. IMO, it runs too high a pressure in too small a case and worse yet, it's almost always chambered in a handgun that was originally engineered around the 9mm. So here we have a hot round with absolutely no room for any sort of error, only NOW it's being launched from a pistol that used to have a .355" hole bored through it... but with it's new .400" hole bored through it. Less metal around the entire circumference of the round. Even less room for error.
I also concur with others that don't care for the recoil pulse which is sharp. It's not that I can't handle or hate recoil (my carry gun is 10mm), it's just more of a bang-for-the-buck sort of thing. I don't care to be subjected to .40 S&W recoil for the .40 S&W performance output.
Still, the existence of the .40 S&W has had a tremendous impact in my continued ability to get a hold of .40 caliber component bullets so that I may easily feed my 10mm Auto addiction. I've been handloading the 10mm since 1992 and I have little doubt that the commercial success of the .40 S&W has done
everything to ensure that I can always find .400" jacketed slugs to load up in proper 10mm ammo.