Well, since this thread seems to be covering all aspects of 5.56x45, here goes:
I finished reading Blackhawk Down the first week of September. It seems to me that one of the major complaints that the soldiers had in Mog was that it took several to many shots (with what I assume to be SS109) to drop each skinny. Overpenetration and a lack of fragmentation seemed to be a real problem.
So, my question is: At under 200 meters would a superior projectile choice be a 55gr soft tip or hollow tip bullet against "soft" targets? Given that we civvies are restricted to hardball only I thought that this might be a good question.
So I would say yes, go with the 55grain stuff, it tumbles, and causes worse wounds.
BTW, the Russians are way ahead of us in military bullet (slug, not cartridge) technology. Their 5.45mm bullets use a hollow space just behind the tip, then a steel penetrator, then a lead "driver". The slug is balanced for accuracy in flight, and as soon as they hit flesh, the driver and penetrator push forward into the air space, causing the center of gravity to flip, and the bullet to keyhole like mad, always coming out backwards or sideways. The Afghans and Chechens really fear them, and call them "poison bullets".
Another "field expedient" for your .223 ball ammo is to take strong wire cutters (dykes) and clip off the front 1/8" of your bullets. This is hell on long range accuracy, but ensures the slugs will be keyholing and tumbling into their targets. I have not done this, but some old VN jungle fighters (close range engagements) told me about it.