a military commanders take on the .223 platform..
and if the target has unfashionable kevlar, at ranges greater than 200m you can only hope to accomplish a wound that my or may not incapacitate or kill..
this is an article written by "Major Thomas P. Ehrhart" a commanding officer in the United States Army. this is his take on the AR platform chambered in the standard .223/5.56 caliber.
http://www.dtic.mil/cgi-bin/GetTRDoc...c=GetTRDoc.pdf
i happen to agree with a lot of what he says, that the .223 starts to become ineffective for killing after about 200m. the reason being that the .223 relies heavily upon the super high velocity of the round and its fragmentation to create the devastating wound cavities required to kill or incapacitate the target. at ranges further than 200m the velocity has dropped below the threshold to cause fragmentation and capability to inflict these wound cavities is greatly diminished. at ranges greater than 200m it has been found that shot placement becomes critical and that anything short of vital shots will not kill and can sometimes leave the enemy combat effective.
but at the greater ranges, being the velocity has dropped to below the critical velocity for fragmentation, the projectile then must rely on hitting vital spots and the transference of energy into the target. the problem with this is that being the standard m855 round deforms little or if at all when a certain velocity has been reached the round is more likely to just pass on through with little transference of energy to the target..
but these are one of the main reasons that for my rifle/caliber selection i do not have a .223 rifle. while the .223 was ok for what it was originally adopted for (close range jungle warfare within 200m or less) it is not ideal for a country that has ranges of upwards of 500m-1,000m. why the .223 is forced as the best and only choice by a lot of survivalist organizations despite its limitations in open country environments is a mystery. there is just too much terrain inside of the US for the .223 to be an effective combat round consideration for survival. and this is what has been found out in Afghanistan with the mountainous and open terrain. most of the time all they can hope to do is keep the insurgents pinned down till CAS or artillery arrives when faced with targets at 300m and beyond. i for one would much rather have an SKS in 7.62x39mm than the .223 for ranges up to 300m. the reason is that even though the 7.62x39mm is traveling slower than the .223, the M43 7.62x39mm at 300m has over 200FtLbs of kinetic energy over the .223. also the larger cross section of the heavier 30cal round ensures that more energy is transferred into the target at those longer ranges.
but i know this post is going to stir up a lot of feelings in people who think the .223 is the end all of calibers. im not here to poop on anyone choice of calibers, nor am i here to poop on the AR platform. if i was given an AR-10 id be a happy camper. im just pointing out the serious limitation to the AR chambered in .223 as a killing round for a SHTF situation. the limitations have been proven in warfare and are well documented.. now if your AO is all wooded area and MOUT where you are within 200m then the .223 would probably shine, as that is what it was intended for when it was adopted during Vietnam. but if your AO has mountainous terrain or ranges greater than 200m, something with more poop downrange should be taken into consideration.