Home Defense with an AK

[benEzra]

9mm penetrates less than normal .223, even in the case of frangible rounds

Lightweight .223 JHP's penetrate somewhat less in building materials than 9mm JHP's, and have less wounding potential on the other side of walls they do penetrate.

Most FMJ-profile frangibles are only designed to break up when they hit something hard (the most common frangible .223 loads were developed to reduce splashback when shooting steel targets during training, IIRC). They're not as fragile on wallboard as 40gr (and possibly 55gr) JHP's, methinks.

Roberts, GK: "Law Enforcement General Purpose Shoulder Fired Weapons -- The Wounding Effects of 5.56mm/.223 Carbines Compared With 12 Ga. Shotguns and Pistol Caliber Weapons using 10% Ordnance Gelatin as a Tissue Simulant." Police Marksman, July/August 1998.