My #3 Son is the firearms/training officer for a large agency.
This agency started with .38, than 9mm, than .40, then .45.
Now returned to 9mm. He reported that the .40 was more effected in OIS than the other calibers. I would have guessed the .45 was.
According to Doc Gary Roberts, among relatively common duty rounds, 180 gr 40 S&W has the best terminal effectiveness.
Beats up guns how?
I have 9's, 45's, 40's 10mm's and a couple other odd ball caliber.
Most of my pistols have anywhere between 500 to 1500 rounds through them, all, for the most, original internals. The 40's are not beat up at all. My Glock 20 has been ran hot through most of its life and for 10mm, it looks as good as new inside.
So what gets beat up on a .40?
And cost twice as much as 9mm?
LOL, you need to find a better supplier.
The 'beat up guns' reputation comes from early 40 S&W pistols that were 9mm designs converted to 40 S&W. The early 3rd gen S&W 40 S&Ws were known for a multitude of problems, and the aluminum frame models were known for cracking frames. The latter was true for 40 S&W SIG P226 that were shot a lot. I've heard some argue that the whole 'overtorqued weapon lights causing functioning issues' was largely a Gen 3 Glock 22/23 frame flex/harmonics issue. Glock finally added slide mass for the Gen 5 G22/23.
Pistols that were designed to shoot 40 S&W from the start like the SIG P229, HK USP, and S&W M&P (really, most post 2000 duty handguns) generally had fewer 40 S&W specific issues.
I think "40 recoils a lot" comes from people whose first experience of the caliber is using a Glock 23. My first shooting buddy had a 23C and I thought it was nasty. Shooting a full mag of SD ammo left my hand "zinging". I've not fired a M&P 40, but given the way the M&P design makes 9mm feel like a powder puff, it has to be nicer to shoot.
I initially dismissed 40 S&W after shooting a Gen 3 Glock 35 that really didn't fit my hands, giving me the famed Glock knuckle. I later got to shoot an XDM 40 S&W, and high bore axis be damned, it was far more pleasant to shoot. I also found 180 gr duty loads more pleasant than 155-165. 180 gr's smoother recoil impulse felt more like shooting 230 gr .45 ACP.
Apparently that OP never owned or shot a 40..........None of what he said it true.........IIffen ya apply the same bullet technology to the 40 as to the 9 the 40 wins hands down........Been a 40 shooter since 1989 when it was first introduced.
There's a flaw in thinking that 40 S&W JHP have improved proportionally as much as 9mm JHP have, and it's that 40 S&W started out more reliable on average, especially in sub 4" barrels. A lot of 9mm JHP offered either shallow penetration (ex. Winchester Silvertip), or inconsistent expansion, especially through heavy clothing (ex. Federal Hydra-Shok).
Comparing Hydra Shok to the newer HST, 9mm went from expanding some of the time to working almost all of the time, along with expanding bigger and penetrating deeper. With .40 S&W, Hydra Shok worked very well from the start! HST will expand a little bigger and penetrate a little deeper. .40 S&W HST still has better terminal performance than 9mm HST, but the JHP performance gap has narrowed.
With all that said, I still think that 9mm is a better choice for most people. For them, the slight terminal performance edge with .40 S&W isn't going to be worth the reduced capacity, increased recoil, and higher ammo costs. They're not insurmountable things, but just not worth it to most people. We also get slightly slimmer guns when magazines are designed around 9x19 and not as 9/40. For all the talk of the P365's magazine design, it's not any narrower than a CZ-75 magazine.