Regarding the .40... Prior to 2012, Our department used to give officers their choice of calibers 9mm, .40, .45 ACP... at that time officers could also choose their duty issue handgun, either a Glock (variety of models) or a Kimber 1911. Our SWAT team could use either the Glock 21 in .45 or the Kimber also in .45. The issued Patrol rifle at the time was a Ruger Mini 14.
In 2011 some of us wanted to revisit the whole duty issue thing and wanted to conduct a bunch of ammo testing and firearms testing to see what was best to actually be using given advancements in technology. The department finally agreed and we scheduled a major Test and Eval event at our range facility beginning in March 2012 and it went on non-stop for a few months. Law enforcement agencies sent reps from all over the country, and Canada to observe, and ammo and weapons manufacturers sent reps from all the major manufacturers to provide weapons and ammo for testing.
At the same time, we were testing body armor as well.
I leveraged the opportunity and got my admins ego fired up in front of all the other agencies and got them to commit to "we will purchase the best, money is no object, the best firearms, the best ammo determined at the end of this testing." And we, the end users, would be able to select whatever at whatever costs. The only caveat was we had to use firearms available to the general public (except for SWAT) and we had to use ammo available to the general public (even SWAT).
We fired all the major brands, in 9mm, .40., .45 ACP, .223 and .308... we shot every available (2012) AR variant, the H&K MP 5 and HK 53, the Ruger Mini 14, and a wide variety of commonly issued duty pistols.
Our testing involved saltwater immersion tests (because we are a port city and Tacoma is the 7th largest container shipping port on the North American continent.)
We fired through typical barriers that we would run into, windshields, residential sliding glass doors, residential windows, vehicle windows, common house construction walls and doors, commercial windows and glass doors, etc. We always used ballistic gelatin to stop the rounds after they were fired through whatever media or barriers. We fired through car doors, you name it.
At the end of the day, after all the data and testing was compiled with the reps present the results were shocking...
We got rid of the Ruger Mini 14's and traded them in for S&W M&P 15s... we chose them because they held up the best or as well as any of the other brands WITH NO MALFUNCTIONS including the saltwater immersion test, at a reduced cost. Essentially the provided as good a product for a cheaper price.
We nuked all the Kimber's out of our arsenal; they rusted and corroded if you looked at them and their magazine capacity sucked.
We completely eliminated the .40 Cal from our arsenal and firearms selection. During the testing it did nothing that the new 9mm +P ammo or the .45 couldn't already do.
Our SWAT team immediately got rid of our MP 5s and HK 53s... HKs customer service sucked (2012) and during the testing the firearms reliability was questionable. We (SWAT entered into a contract with COLT as a result of this testing for their full auto M4s). Additionally, the 9mm coming out of the MP5s caused "over-penetration" concerns for us during the testing... it went through house walls, vehicles, busses, etc. and kept on rolling. We can't have that. We switched to the .223 (Colt M4 and S&W M&P 15)
Glock became our ONLY issued duty pistol... it smoked everyone else in the testing, lack of maintenance requirements and ease of maintenance and saltwater immersion tests.
Our SWAT team immediately switched from the .45 ACP (which we had previously been mandated to carry on SWAT) to using 9mm Speer 147 gr duty ammo. In the testing through the various barriers, ballistic gelatin, etc. it smoked the .45 (hard to believe and accept but the proof was in front of us).
Point Blank body armor became our new duty issue, with trauma plates.
Everybody has their personal faves and preferences, but I'm a data guy and after participating in this extensive testing event I became a 9mm guy. A lot of people look at charts and manufacturers "data" and bullshit... but we actually looked at ballistic gelatin after firing through a car windshield or car door. In real world testing, regardless of what the manufacturer said on paper the results were hard to argue with.
Our duty ammo became Speer Gold Dot 9mm 147 gr.; Winchester Ranger 5.56 55 gr bonded; Hornaday AMAX 168 gr .7.62
Later on, we conducted a similarly large sniper rifle T-n-E event for our SWAT team with reps from all over coming in. more on that another time.
Attached are some pics from our testing event.