The Viper tricks are far better penetrators.
I can't prove this through any science I've done, or the laws of physics, but I agree with it.
I like the broader cut of the Viper on bigger animals, and I have broken rib bone with them, and had a clean kill within 30 seconds.
IMHO, the Viper is a bit tougher by design than the standard four blade, but it's really a matter of choice. Either will/have killed a bunch of game.
