I have a 140 grain copper mono (Barnes XPB) that shows consistently good penetration in any test I've ever seen -- my own or that of others (it's loaded by Barnes, Federal, Buffalo Bore, and others). I have expanded bullets that I would say are 0.68" in diameter. If I measure the outside of the petal to the outside of the opposite petal, it's more like 0.73" but that would only be at the tips of the petals. So the sectional density of the opened bullet is something like 140*0.68^2 or 0.43. Even if we were to take a 158 grain XTP expanded to .58" the sectional density is .067. That's a bullet that is known to penetrate denim and 22 to 24 inches of gel (with factory Hornady loads from typical revolvers).
The sectional density of a 120 grain bullet at .357" is .135 -- about twice that of the XTP. Even the sectional density of a 90 grain bullet at 9mm (.355") is 0.1 -- still more than the XTP. The wimpy 68 grain pill? 0.77 -- more than the 158 grain XTP.
Just like traditionally accepted bullet weights don't translate from fragmenting cup and core to monolithic designs that keep their integrity, traditional JHP bullet weights for handguns don't translate to non-expanding monolithics. We would have scoffed at 90 and certainly at 68 grain bullets for 9mm. Fackler railed on 115 grain 9mm bullets and the high-velocity "energy transfer" fad. But why? Where were these fast and light handgun bullets actually deficient? They were deficient in consistent penetration. They were vulnerable to blowing up on impact and under-penetration. Fackler preferred the 147 grain loads with their greater sectional density and low probability of under-penetrating.
Fackler and the heir of his theories SSA J. Buford Boone III established the current prevailing criteria of jelly penetration and expansion as the rule by which handgun ammo is judged. With these theories prevailing at the FBI (through Boone's influence), it has become the defacto standard for all high-volume US defensive handgun ammo makers. Non-expanding ammo could never meet the required criteria because "wounding" has become totally disregarded in favor of "expansion in gel." There is no "standard" or objective criteria for evaluating "wounding" whatsoever -- only penetration and expansion in gel.
Federal/Vista, for one, has shown a willingness to game the system. "We can make, with this modern technology, a bullet do just about anything we want it to do." -- Chris Laack, Product Line Manager for Handgun Ammunition for Federal/CCI/Speer. Witness the "30 Super Carry" -- I can't imagine Martin Fackler being impressed with a 100 grain 32 caliber projectile, but Federal has used its "modern technology" to make it do in gel what Fackler wanted it to do.
Do Xtreme Defense bullets show in any test lower penetration than what we could expect from bullets that meet FBI specification? Has even the comically light 68 grain 9mm showed poor penetration in gel tests?
