Some interesting gems in this article

Mr. Perfect

1) 9mm penetrates too much (e.g. sheetrock)

2) LEOs don't need full auto; semi auto is safer

3) SWAT are more 2A minded than other LEOs

There is a lot of horn tooting as should be expected, but overall this is a good interview.

https://www.arbuildjunkie.com/bill-blowers-tap-rack-tactical-swat-ars/

Don McManus

While I have not tested either, it seems odd that a 9mm projectile will go through 2 - 3 times the sheet rock that a 5.56mm projectile will go through.

Mr. Perfect

Don McManus said:

While I have not tested either, it seems odd that a 9mm projectile will go through 2 - 3 times the sheet rock that a 5.56mm projectile will go through.

I guess it's the notion that 5.56 is going to tumble and break apart vs. FMJ 9mm?

Ricci.Wright

I would guess bullet construction is a contributing factor. 55 gr .223 HP verses 9 mm ball for example.