I am quite amused that anyone would go with a FASTER cartridge to get MORE penetration. They obviously are looking at the problem ass backward.
At police engagement ranges, impact velocities are almost the same as muzzle velocity.
We have proven a bizillion times that the faster a bullet impacts a surface, the more that bullet will want to deform/expand, in some cases tumble (ala 55gr 223 in a little Asian jungle). Not so good for busting through stuff then continuing accurately on your way.
What is needed is a very TOUGH bullet going at moderate velocities. The trick is still to balance the needed expansion so that the bullet doesn't whiz through the barrier/target/surrounding passersby.
The Barnes X seems to be a very good option with a variety of reports showing they will work very well on glass and light auto body parts. I have no info on body armour but expect performance to rival FMJ's.
The downside is that overpenetration on soft targets is a very real risk.
As for lights out, again bullet matters more then cartridge. From the volume of ads and such, the Hornady TAP ammo is being very well consumed by SWAT and other stop bad guy units.
Answer- a most wonderfully accurate rapidly expanding family of bullets - AMAX. Bullet goes in, no big bullet parts, if any, come out. The interior damage is explosive to say the least. The human body just doesn't deal with that much shock. Lights out.
A beanie shot will also have a very low chance of dangerous shrapnel/over penetration as the bullet is nearly fully fragmented. Not something you want CNN taping though.
For this application, the 223 reigns supreme. Think bad guys meet gopher bullet.
Barnes, Swift, and others are now making some very tough premium bullets catering to the 22cal big game hunter. They should work very well in barrier penetration like their 308 brethren.
If someone is to be fully prepared, they need more then one bullet in their possession. Like the 12ga, just load what you need and have lots of other options as back up.
I would be very concerned that a pro would need a 300WM. For a soft target, way more then they will need and collateral damage risks are very high. For hardened targets, the 300WM is not likely to do the job and you may as well go right to the yummy BMG!
or maybe the politically correct 416Barrett. Or the 338 Lapua/RUM.
That'll leave a mark....
Jerry