At least from what I have read, and I don't remember where but a 5.7 supposedly won't go through a normal sheet rock wall and that is why SWAT teams like the rifle version of the 5.7. This is due to the bullets tendency to tumble after entry. (I suspect it would not tumble in something as dense as wood) I would love it if some one would test this. It also tumbles in the body making a larger wound and not over penetrating which is one of the reasons why the Secret Service uses the 5.7.rm9792 wrote:You will likely never own a P90, they are NFA. You can get a PS90 which is semi and long barreled. That being said, the 5.7 penetrates way too much for defensive use. I have shot mine thru 2 new 2x4's stacked together. Thats a lot of penetration. I havent seen the ballistics of flesh but imagine it would hit like an icepick and go right thru to the bystanders.
As far as the Taurus clones go i would prefer them over the beretta as the fit and finish is the same or better on the ones I have owned, plus the Beretta safety is "backwards". Pick up and feel a SS Taurus, they are very smooth sliding and trigger is not bad at all. If you do get the Beretta you can get the matching CX4 carbine and share mags and ammo.
I'm no expert on any of this so if I have erred please correct me.