The far better question is why they need assault rifles?
A suppressor is actually a good thing to put on any weapon. That's why they're becoming standard in the military. Guns are unbelievably loud, to the point that they can cause serious and permanent hearing damage to people around you when you fire them. If you're accepting the premise that an armed police force is a good thing (I disagree, but that's a separate discussion) it at least makes sense to minimize collateral damage. The sound of gunfire is especially dangerous indoors; if an officer was forced to fire their weapon in an environment like they could actually seriously injure innocent bystanders just from the noise alone.
On the other hand, collateral damage is exactly why a 5.56mm carbine makes no sense as a police weapon. Those rounds will go straight through a human body, straight through a brick wall, and still be lethal. You could end up killing someone you can't even see. It used to be that when law enforcement wanted extra firepower, they used submachine guns and shotguns, weapons with very little potential for overpenetration. But then police forces all started freaking out about the idea that every criminal was going to be wearing level 3 body armour and demanding to use the same guns soldiers use (not helped by the fact that cops in the US are allowed to buy surplus military equipment at knockdown prices).
This doesn't come from an operational need, it comes from the fact that every cop wants to cosplay at being military, but without all the hardships that actually come with that. That's why you see federal agents and SWAT all running around in multicam and other military camo patterns, despite the fact that those patterns really don't do much of anything in an urban environment. It's all just dress up to make their peepees feel bigger.
Well said. If you've ever been next to someone at an indoor range firing large caliber rounds without a suppressor, it's very unpleasant to be near them if you're plinking 9mm or 22lr.
I support taking supressors off the NFA (and also abolishing the NFA altogether, but that's another argument). Calling them silencers is incorrect. They're safety devices. Some states don't even classify them as firearms. Any supersonic round is still loud enough to require ear protection.
YES. That is the most annoying shit ever. I'm just tryna have a good time practicing good technique with a handgun and I have to sit and listen to some moron spray hundreds of dollars worth of ammo away so they can feel like they're the coolest dude at the range. Then they leave and we all look around at each other like "thank fuck that asshole is finally gone eye roll emoji"
There are different kinds of 5.56mm ammo, they don't all have the same construction or behave the same way. We don't know what ICE are loading.
Even M855 green tip (which is what it sounds like you're describing, or at least some similar variety of FMJ soft core round) can pierce lighter body armour and still be lethal. That means against an unarmoured target it's going to have very little problem going in and out of a human body.
While I'll grant that most softer varieties of 5.56 will be stopped by brick (again, we don't know exactly what ICE are loading, but fairs fair, it was somewhat of an overstatement on my part), they will certainly have no difficulty going through drywall, wood, and other visual obstructions that could be concealing an innocent bystander. While it's certainly true that something like a 9mm can also penetrate many of these obstructions, it will not retain nearly as much lethality when doing so, and it simply makes no sense to increase your risk of injuring a bystander every time you fire for basically no gain. If you fire an AR-15 inside a building (which, y'know, is where a bunch of people doing no-knock raids expect to be spending a lot of their time) you have a very high chance of killing an innocent bystander you couldn't even see.
For more on this I consulted my wife who confirmed that she's been shown videos in training of 5.56 going through multiple layers of dry-wall and still retaining lethal velocity. You can see this in this video here (https://www.youtube.com/watch?v=j3BlRPtCj2E) but know that this is also what professionals are taught about their weapons when considering targets, over-penetration and cover.