The 9mm vs. .40 thing was very controversial among the office leadership. I am a R.Moran disciple and go with the pragmatic approach.
I honestly didn't care one way or another from a terminal ballistic perspective which one we chose. They both work. And personally, the recoil of the .40 has never bothered me. Similarly, I am comfortable with the accuracy, reliability, durability and shootability of both the M&P and Glock pistol.
My recommendations during this project were all pragmatic. What is the best choice from a lifecycle cost, logistics, maintenance, supportability, and shootability standpoint? I looked at what the new hires were showing me on the range for ability and interest. I looked at our hiring pool. I looked at past scores and grouping locations. I looked at what scores guys were posting when they brought their own guns to the range and shot on their own time. I looked at what guys are buying with their own money.
In order to bring some objectivity to the discussion I designed a evaluation procedure. We did a shoot off between M&P Gen 1 .40 with and without RMR / Glock 17,19, 22 with and without RMR06, and with and without fiber optic front sights. Each deputy shot an untimed five shot group with every combination at 15 yards. Target was a 4" black dot on white background. Eight deputies with varying levels of skill participated. Deputies had all fired our standard 50 round qualification with the issued M&P .40 immediately prior to shooting in the evaluation. I measured groups, but the data I presented at the office was simple analog: Bigger/Smaller for each variable.
9mm printed smaller groups across platform brand, size and sight type.
RMR equipped pistols regardless of caliber or base shooter skill consistently printed smaller groups than non RMR.
Full size guns (G17/22) printed smaller groups than compact (G19) M&P fits in between the G22 and G23 in grip size, although it mirrors the fullsize G22 in magazine capacity.
Glock 22 .40 consistently printed smaller groups than M&P 40 unless deputy skill level was high. In the case of high skill, group sizes were statistically equal.
Fiber optic front sight equipped pistols tended to group better than night sight equipped pistols.
We really should have had a M&P9 included, but none were available. We should also have had M&P 2.0 pistols to include, again none were available.
Caveat: This is all based on analog scoring which allows us to look at trends. As I looked over the targets and compiled results, there was not a single combination that was objectively a poor performer. Any group fired was capable of staying within an 8" vital zone at 25 yards. This is a reasonable minimal performance expectation of any person capable of passing standard LE physical and cognitive tests.
Based on the trends established within these parameters, I suggest LE agencies adopt 9mm full size pistols which are equipped with RMR type sights or at minimum fiber optic front sights. Within these results, Glock may have a slight performance edge over the Gen1 S&W M&P.
We will likely repeat the evaluation once the M&P 2.0 CORE 9mm pistols arrive. Ideally, we will include a Glock Gen 5 so that we are comparing similar advancements in design.