LE agencies using 9mm
Dane County WI issued Glock 17s and the 21. I've heard second hand that they now issue only the 17.
The UW department, a division of the WI State Police, issue the 19 or 17.
The Madison WI PD issues the Glock 19 or 17, but allows officers to carry their self-purchased 22 or 21. Weapon-mounted lights have been a serious issue, causing malfunctions with the 22. I hear, second hand, that if a weapons light is used, it can't be on the 22 due to malfunctions.
I have an ancient 22 and an equally ancient 21, no rails. They are rock solid reliable.
One of our sons is a LEO, issued, I think, Winchester Silver Tip 9mm ammo. He says he does not feel under-gunned. However, he does have an AR in the trunk . . ..
In the '80s, 9mm ammo was generally considered not as effective as larger calibers. My employer issued the Sig 228 and 226 and, later, the 229/357Sig, sometimes the 220/.45ACP. When the 357Sig ammo became available, it offered a provable improvement over 9mm and even .45ACP. I took to it right away, and was issued one of the first 229s to come into the country. I liked it so much I bought my own. I also wrote Sig telling them they should make the 226 in 357Sig. That didn't happen until I no longer cared, and 9mm ammo, in my opinion, has caught up with anything the 357Sig offered except a flatter trajectory and better terminal performance at distance. I don't really need either any more, though I still carry the 357Sig because I shoot it well.
When I run out of 357Sig ammo - about 10,000 rounds left, I'll probably go to the M&P 9mm.