the 7.62 wouldn't work in urban settings. too much kick, even on burst.

Listen boys this is like comparing a pellet gun to a .22L.R.  We all know what the difference is.  .223 vs. a .308  my dog could answer this one.  Penetration is easy.  You have to think like the military.  Cost, Weight, Accuracy, Ease of training, Confidence.  For Example:   Take an eight year old boy out shooting.  Give him two rifles.  One a .22 and the other a .300 Winchester magnum.  Make him shoot a box of each.  It is my bet that this child not only will love the .22 but will be able to shoot consistent head shots with it.  The .300,,,doubt it.  Militarily speaking I doubt the best strategy would be to keep shooting a three inch concrete slab until it disappears just to get to an enemy behind it. I bet they would want you to get a better position and make a head shot.  I can also guarantee you that a well trained marksman with a .22 can dump more people than someone who thinks their 5.56 or 7.62 is the best penetrating round.      peace

The never-ending debate of 5.56 vs. 7.62...

I don't think that Roe deer, an animal that maxes-out around 60 lbs. (~27 kg), is much of a comparison to a human being. A North American whitetail deer would be much closer in weight and skeletal strength. For that game, the .223 is marginal.

But comparing deer cartridges isn't really what this discussion is about. It's about the military 5.56mm NATO M855-type round and its ability to penetrate. Under all but the most controlled conditions it is sadly lacking. This cannot be seriously questioned by anyone with a shred of first-hand combat experience with the cartridge. It does very poorly against concrete block, brick, live wood, etc. In other words, common materials used as cover. It cannot even be relied upon to penetrate windshields. (Just ask anyone who has manned a vehicle checkpoint in Iraq.) U.S. Federal law enforcement agencies have adopted special 5.56mm cartridges designed with this in mind; however these rounds cannot be used by the military due to international convention. In contrast, the 7.62mm NATO Ball cartridge is more than capable of effectively defeating any of the barriers I've cited. Additionally it will defeat modern hard body armor with far fewer hits than would a 5.56mm weapon.

But as the previous poster noted, .30 caliber weapons/cartridges can be significantly more unwieldy and heavier than comparable 5.56mm arms/ammo. That's the conundrum - Do we issue everyone an M14 or L1A1 that will give exceptional ballistics at the expense of weight and number of rounds carried? Or do we continue to use 5.56mm carbines and accept that the individual soldier will face many instances when his weapon won't do the job against an enemy behind cover? IMO it doesn't have to be an either/or situation. Something like the Springfield Armory Scout, DSA's SA58 FAL PARATactical or any of the AR10-type weapons such as the Armalite 7.62mm Carbine give up little in handiness to the M16 but increase the individual soldier's lethality by a wide margin. Nevertheless, ammunition weight can still be a problem. A soldier will still carry fewer 7.62 rounds than 5.56 for a given amount of weight. But since he's now equipped with a more potent weapon this may offset the number of rounds carried. Another solution could be the adoption of 6.5mm Grendel with an ~120-grain bullet. This would give a significant boost in power compared to the 5.56mm but allow more rounds to be carried than a 7.62x51mm-equipped soldier. An added benefit is that an army fielding the M16/M4 only needs new upper receivers, bolts and magazines to make the change. 

justbill,