Why is the IRS buying .40-caliber submachine guns?
View: https://www.youtube.com/watch?v=tGvYlyr6_54
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Armed federal agencies. Shooting from the hip with this one - if you'll pardon the expression - but at one time you know who was eager to get their hands on as many Thompson Submachine guns as they possibly could? The Post Office. Treasury Agents too, but you might be able to get your head around that.
The Post Office? Yup.
Speaking strictly (with geekery) about the use of .40 caliber submachines guns - not about who is using them - his is an old topic. A
submachine gun uses straight walled pistol caliber ammunition. Full machines guns generally use bottleneck rifle cartridges. Going back some decades it was not unusual for a police officer to carry only a revolver and shotgun in the cruiser but there have been instances where lives have been lost for lack of sufficient armed response. Now it's a high capacity semi-auto sidearm and a carbine of some sort, usually an AR variant. A carbine (short rifle) , BTW, that is generally using a rifle cartridge.
After a particularly nasty incident in the late 80s the FBI adopted a new 10mm cartridge - a true .400 or 40 caliber round - to give their agents more firepower on their belts. They are a trend setter in the industry. It had some advantages over the 9mm and .45 ACP is competed against but was ultimately found to be much too powerful and hideously overpenetrative. Meaning, you can shoot right through quite a lot much too easily and it had a lot of recoil. So, an intermediate 40 caliber round was developed that was physically shorter with a smaller primer that had less recoil and could be adapted to the frame size of existing design so that smaller people can use them more readily. Smith and Wesson called it the .40 S&W. Handloaders call it the '
40 Short & Weak' but it's increased mass and magazine capacity over it's predecessors meant that about every cop in the country carries one now.
ARs are dangerous in urban environments, as we know all too well. The idea of having a pistol caliber carbine on hand,
one that might even use the same magazines the officer already has on their belt, is an advantage. Short, light, deadly and less apt to cause collateral damage downrange. Marlin made a Camp Carbine like this and Beretta has a really stupid Storm series that did this. It's always been been desirable, not exactly a Holy Grail, but something worth spending some $$ developing and sometimes a more affordable alternative to smaller agencies. Add to that an entire generation of combat in which Special Forces have found that combination useful and what we see here is a sort of trickle down.
Militarization - all the fancy hardware didn't do much for the lard asses at Uvalde, did it?