(from Sep 2014)
For people who want to defend their homes, the question is what effect would a stray shot have, if it missed the bad guy and instead penetrated through a wall -- would it pose a threat to someone in an adjoining room, or a neighbor in the next apartment or condominium?
While the answer is normally an overwhelming "yes" with conventional hollowpoints or FMJ bullets, in this test I try to test some different types of ammo. Federal's Guard Dog is an expanding full-metal-jacket bullet that claims to minimize overpenetration through walls. DRT classifies their ammo as a "penetrating frangible"; DRT says on their website that their ammo will penetrate through sheetrock, but will a compressed-powder frangible bullet be a safer choice for minimizing the potential danger through walls. And Liberty Civil Defense ammo is a lightweight fragmenting bullet that normally disperses into many little fragments upon contact with a body -- will it prove to be less dangerous after going through a wall?
Finally, I also throw in a shot of birdshot from a Taurus Judge. Birdshot (especially birdshot from a handgun!) makes for a weak personal defense round, but perhaps the tiny pellets will prove to be incapable of penetrating walls.
In this test I constructed a rig to hold four sheets of 1/2" drywall, basically simulating two interior walls. To assess the potential lethality of the bullets after passing through the drywall, I set up a block of calibrated 10% ordnance gelatin to catch the bullets and measure their residual penetration depth. A bullet that penetrates only a couple of inches of gel may be capable of inflicting a superficial wound, but would be unlikely to cause a serious injury in most cases; however if the bullet retains enough energy to penetrate a good 8" or more, it should still be considered lethal.