I don't have much experience with the .308, but I do have extensive experience with the .223. The one thing that is always ignored when the .223 is discussed is the rifling twist of the barrel it's being fired from, and it makes a tremendous amount of difference. With 55 gr FMJ ammo, you can have a barrel twist anywhere from 1/14 down to 1/7, and there is one hell of a lot of difference in the wound characteristics with the same bullet fired from the different barrels.
A 55grFMJ bullet from a 1/14 barrel is just barely stabilized, and will flip end over end upon hitting almost anything. One from a 1/7 barrel is much more likely to go straight through, with better penetration and wounding, but at the cost of lessened energy transfer and reduced stopping power due to the bullet exiting with more residual energy. This is one reason there are such wildly conflicting stories about the M16 either being next to useless, or the finest killing machine ever issued to the military, as the performance of the bullets varied so greatly.
The one most people know of is the M16A1 (or the civillian version SP-1), issued with the 1/12 twist light barrel. This rifle had the reputation of being next to useless in brush, as you could fire a whole magazine at something you could see through the undergrowth, and never hit it. It also had the reputation of being a stone killer if you had a clear shot, leaving a small hole on entrance and huge gaping wounds on exit. This was mostly due to the bullet being just barely stabilized in that slow twist barrel, they were easily deflected by brush, but the same thing that made them so aggrivating in the brush made it a remakably effective weapon in the clear, the round had an almost unbelievable wound channel in soft tissue due to the unstable bullet.
I have no proof of this, but I suspect that the rapid twist of the M16A2 and heavier 62gr bullet were partly to increase the penetration, and partly to produce more humane wounds, which, to the military mind, is preferable to killing as it causes the enemy to overload his support system, reducing his morale and effectiveness.
I know the story about the long tracer bullets, but the ones I've fired seemed to go no better in the A2 than in the A1, with lots of flyers in either one, so I'm not really sold on that particular story.
There are some local coyote hunters who illustrate this theory well, they all like the 1/7 barrels over the older 1/12 as there is less chance of leaving gaping holes in the pelts. One fellow who started with an SP1, ruined a few pelts and was of the mind that the .223 was too brutal for that type of hunting, but changed his tune around with the installation of a newer 1/7 barrel. He is a happy camper now, as he always liked the rifle, just not the bullet.
If you can fire a 1/7 and a 1/12 side by side with 55 gr FMJ ammo, try them on water filled milk jugs sometime, you'll see the difference. You'll really see it if you place two or three jugs in a row front to back and shoot straight at the front jug. Ballistic gelatin is better than jugs, but most people don't have any. You can't use 62gr ammo in a 1/12 barrel, it won't stabilize at all and will be going sideways at about 50 feet. In the 1/7 barrel it penetrates even deeper and gives a straight wound channel. Hope this helps.
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With my shield or on it...
I keep hearing people say that the .223 has better stopping power inside of 150yds then the .308 I would not want to get shot with either but I would think that the .308 would have more stopping power at any range. I don't think there is anything wrong with either round and there are rifles that I want in both. I have heard that the ballistic reports of the .223 yawing inside the body are not true. Is this what people are talking about when they say that the .223 has better stopping power inside of 150yds?