Although it works different, the concept is the same as Federal�s EFMJ. Traditional hollow points rely on hydraulic pressure to open up, these cartridges change the expansion to impact expansion. The advantage of this, like with high powered rifle ammunition, is extremely reliable and consistent expansion. The disadvantage is barrier penetration.
A standard hollow point wont (or shouldn�t; usually doesn�t) expand in barriers because there�s no hydraulic pressure pressing the sides of the hollow cavity outward. This keeps the frontal diameter to a minimum and allows maximum expansion. Then when soft tissue is hit, the water in the tissue fills the cavity, and it expands.
For law enforcement, this ammo would be a mistake. But for home defense, it would have the advantage of reduced penetration with maximum expansion.
It�s a good alternative, and it�s nice to see we have even more options. I don�t think I�ll be changing soon. I just wish they made it for .32 H&R Magnum, which just plain doesn�t expand in short barrels.