The thing about .223 rounds disintegrating in drywall(Actually, this started during the WACO Seige and it was two layers of one-inch thick plywood with w 4" dead-air space) came from using 55 grain .223 ammo with the wrong twist. The rifles the Branch-Davidians used had 1 in 8 twists I believe( Might have been 1 in 9), which is way too fast for the 55grain bullet.This caused them to spin too fast and over-stabilize. The more centrifical force on a thin-jacketed bullet there is, the easier it comes apart when it hits an object.
For the record, in a properly twisted barrel(1 in 12) a 55 grain .223 will completely penetrate a cinderblock at fifty yards. This is with a standard 55grain lead-core spitzer. With a 1 in 8 or 9 twist, it will blow up on the surface of the block.
Most M4gery rifles and such made nowdays run a 1 in 9 twist for the 60 grain class bullet. Twist is tied directly to bullet-weight and velocity. The heavier the bullet the faster the rate of twist for optimum stability, in .223s this is amplified by the very small bullet, even in the heavier for caliber weights. I've seen 63 grain .223 bullets fired in a 1 in 12 twist keyhole at 200 yards.
As for
s' question in the chat, I would not recommend taking a chance of bullet fragmentation to stave off over-penetration. I know you young fellas all think the M4 is a badazz weapon and ultra-cool but, it makes a lousy home-defense gun. I saw a lot of through and throughs in my day with this round and that was with the 55 grain bullet inside of fifty yards.