Yeah, thats my concern for frangible ammo but from what the article says is that the EPFMJ round was developed for penetrating barriers and then 12" of flesh.(if I'm reading it right)
" Over three years ago, the Research Group of Federal, under the leadership of Dave Longren, Bruce Warren and Larry Head, began a serious analysis of the performance of all hollowpoint bullets of every manufacturer, including Federal's Tactical and Hydra Shok. The validity of the FBI test protocol had long been established and with the assistance of the Law Enforcement and Military Sales division of Federal, which gathered actual shootings information from agencies, the need for a more consistent "through barrier" projectile became apparent. In a joint program with Tom Burczynski, of Experimental Research, Inc., Federal focused its efforts on the FBI events that included heavy clothing, plywood and wallboard. They knew that the hollowpoint had to be capped or covered, and yet achieve the expansion characteristics that the LE community demanded from current bullets. The solution became the new Expanding Full Metal Jacket (EFMJ) projectile that Federal introduced at the IALEFI and IACP conferences in the late fall of 1999. "
"All production and preproductions samples met the FBI minimum penetration criteria of 12 inches in the mediums tested. "