From a standard pistol round? (Not getting into deep-penetration rufle shots or anything.)
And, this may be more an opinion, but to followup, do you think one could make an effective street weapon by cutting a hole in a police shield and sticking a sawed-off (or maybe an over-under sawed-off/carbine, if they make them or are buildable,) through the center, whereby you could fire through it and not be a target yourself (combined of course with wearable bullet-proof shielding.)
Not really. Many are made out of Lexan and similar “bullet-proof” plastics, but in that thickness, they might stop bird shot or a .22.- not anything more powerful. They are there to stop rocks & bottles.
I thought you were talking about the shield on their uniforms…
I coudn’t figure out why you’d want to stick a gun barrel through it.
Time to go home I guess…
No, I thought the same thing. And I ain’t going nowhere! 
That’s what cops get for calling them “shields,” instead of “badges.”
Peace,
mangeorge
The big riot shields are not bulletproof but they’re meant primarily to be used like the shields of a Roman legion, i.e. all the cops form a tight unit and push forward, driving back the barbarian/rioting hordes. I had a chance to see an RCMP riot squad training one day. At first, it seemed kind of odd for them just to march in a big circle, banging their batons on their shields in time, but it occured to me that a WHACK WHACK WHACK sound would cut through the mayhem of a riot and might be able to win the psychological battle before the sides clashed.
Also, on the Roman Legion tack, would they resist a gladius?
If you tried using a stun baton on one, would it conduct to the officer holding it?
Please google “body armor” and/or “rifle plates” (I think - modern body armor can stop 1 round of any pistol (with exceptions for cannon), but will not stand up to serious civilian hunting rifles, let alone combat weapons.
Yes, one round - last I checked, they all said “if the perps nails you in the same spot a second time, bye-bye”. The rifle plates/inserts fit in pockest of the lightweight armor to stop serious ammo - it is, however quite heavy, and the weight of an entire suit of the stuff would prevent much movement (see Hollywood bank robbery for why that stuff is a bad idea).
I’ve wondered that too, if police plexi-shields could resist “white weapons” such as swords and spears. Although I suspect the answer to that is moot since at that point I think they’d break out their sidearms.
(OTOH, ISTR that body armor is not as good against white weapons as was good old fashioned plate and chainmail, so if they could get around the shields, sayonara.)
Hijack: I recall several stories about bullet-proof vests not being knife proof (one that sticks in my head is from News of the Weird from several years ago when two Russian security guards got drunk and one stabbed the other to see if his best would stop the knife. Of course, it didn’t. I also recall hearing something similar during the Olympics.
What’s the reason for that, the knife easily penetrating the body armor that is? I presume that the plates (which are ceramic or titanium IIRC) would stop it, but just a straight-up Kevlar vest?
I’ll wager I could exert more force on a knife with my arms, torso and legs over a half second period than your average pistol round produces when it is fired.
I’ll bet that’s the reason.
Go to Google (or search engine of your choice) and check out body armor - for instance, Kevlar ™ is a fabric which, when presented with a (blunt) bullet, will stretch to absorb the energy imparted - BUT: being a fabric, it is easy to cut - it will distribute the kinetic energy of a bullet to the underlaying (nowadays - as of a few years ago, at least) ceramic material, but will easily shear under a blade - this is not steel, folks - a sharp point or edge will sever the threads.
There are shields available that stop small arms fire. If you google for “ballistic shields” you will find many sites such as this.
Basically, the point of a knife (or worse, an ice pick) puts a really huge amount of force in a very tiny place, it breaks the fibers which then tear.
There is also the “cutting action” of a sliding sharp edge (vs. the compressive action of stabbing with a sharp point), which is quite different on a molecular scale. You are quite correct, however, as far as your argument goes. For this reason, Kevlar vests are significantly less good at blocking a small caliber round that a higher power large caliber round.
My training is obsolete, but in the early days of Kevlar vests (late 70s-early 80s) a standard vest was 9 layers of 90 (? - my memory fails me on this detail) denier Kevlar weave. A .45 pistol round might penetrate 2 layers; a .38 might penetrate 3; a .22 pistol round might penetrate as many as 4-5., even though it packs a lot less “punch”, simply because it’s “pointier”. A .22LR would penetrate further, and with some luck (good or bad), a high power ,22 round might make it all the way through. I still have “Stinger” rounds from those days, which had a core that was pointier still, and were said to be very effective against the Kevlar vests of the day. [Not that I’d fire a 25 year old round, or have any reason to do so, much less penetrate a vest]
Mangeorge: regarding shields vs. badges - although both terms are, for all intents and purposes, interchangeable, all departments do, officially, term theirs as one or the other. While there is no “rule” as to how or why they they make the decision, the term “shield” is used mostly by older departments in the northeast (sorry if I’m being picayune)
As far as ballistic characteristics of shields (the things carried, as opposed to those worn), the following generally applies re the OP:
Clear “riot shields” used by cops during protests typically offer no ballistic protection
Tactical shields (the type used by “SWAT teams”) always offer a level of ballistic protection. Most are capable of stopping even the most powerful rifle rounds.
As far as why knives are able to penetrate the type of bullet-resistant vest used by the average patrol cop, the reasons stated by other posters are generally correct (i.e. the incredible force generated on the tip of the knife/pick both separates and/or cuts through the fibers)
As far as mounting some sort of gun through a hole in a ballistic shield, its been tried. While it seems like a good idea, it hasn’t worked out well in practice because it’s unmanageable and very difficult to aim. The addition of the gun adds weight to what is already a heavy, unwieldy shield.
Most departments train their officers to shoot a pistol around the side of the shield in circumstances that warrant. I know this might sound like an even more inaccurate way to aim, it’s not. In the same way one can instinctually point at a distant object with a great deal of accuracy, so can a shot be fired (especially with some training)
Isn’t it pretty rare for cops to be using shields and firing guns at the same time anyway? At riots the cops discharging the non-lethal weapons are usually behind the ones with the shields.
Shields as used by S.W.A.T. teams do more to enhance the “shock and awe” effect than anything else, I’d think. But all I know is what little I see on TV.
Shooting from behind a tactical shield is more common than you might think, and is the scenario that I was referring to. Riots (and riot shields) are an entirely different ball game.
As far as “shock and awe,” the tactical shields used by SWAT teams are for one purpose only: to protect the cops. If they are somewhat intimidating, so be it. But that’s an ancillary effect. Rest assured, the only reason a real, non-TV, cop carries a tactical shield is because it can mean the difference between life and death.
So, asc165, you think you know more than tv, huh?
Yeah, right.
Actually, discharging a weapon at all is the exception, not the norm.
It was actually ROTC cadets and they weren’t drunk, just young and tragically stupid. According to police in Dahlonega, Ga., ROTC cadet Nick Berrena, 20, was stabbed to death in January by fellow cadet Jeffrey Hoffman, 23, who was trying to prove that a knife could not penetrate the flak vest Berrena was wearing. Berrena suffered a fatal chest wound and died on the scene. I remember when it happened, the town was devastated.
Sadly this has become such an internet joke that I can’t find the original news item anymore, only a lot of Darwin knockoffs. Here is all I can find that isn’t filed under “darwin awards”.
http://www.overbylaw.com/pages/6/
$300,000.00
Military Hazing/Wrongful Death
Cash Settlement - 10/15/98
Estate of Nicholas P. Berrena v. Jeffrey Michael Hoffman
Wrongful death of a young man occurred when he was stabbed by Defendant when Defendant was attempting to show that a knife could not penetrate a flak jacket.
I’m not a cop, but I would think that they would generally try to avoid firing their guns in the sorts of scenarios where riot shields are being used–i.e., chaotic confrontations with lots of people running around. It seems like there would be a very high risk of shooting someone other than the person you’re aiming at.