The term "small arm" or "small arms" refers to a weapon easily carried and used by an individual. That would included rifles and pistols of any caliber as opposed to crew-served weapons, weapons mounted on machinery, towed guns, bombs, etc.
Actually, small arm today is considered .50 bmg and under. You are partly correct, because most will argue that a .50 sniper rifle (SASR) is man portable. You know what your talking about, but we don't want to confuse the ones that think a 240G mounted on a humvee is NOT small arms... IT IS.
Anyhoo... I've stayed away from this one because this is about the 7th "is 5.56 good enough for our military" thread. They're almost predictible, because everyone I see settles on shot placement. Then the shot placement post is touted a bit later on the accuracy of our troops and how little marksmanship training they get. And then that turns into people trying to solve everything that is wrong with the military...
I'm sure most of you know that we have 5.56 for a reason. It is an assault rifle cartridge. An assault rifle is designed to be a small and lightweight, man-operable, close to intermmidiate range rifle that allows reasonably controllable full-auto fire from ANY shooting position. 7.62 is an awesome round with excellent terminal ballistics. There are very few cases that someone takes a few 7.62 rounds and doesn't die shortly thereafter. BUT... let's look at what 95% of 7.62 rounds are fired out of. A belt-fed weapon. Most of the time where one 7.62 goes at least 5 more follow, even during a fast traverse or search fire.
I would like to see something better than 5.56, simply because I know we have the technology to make it happen. I think the 6.8 program WAS going in the right direction, but one of many reasons why that didn't take is because the Marine Corps purchased quite a few new M16A4s about 2 years ago that are all chambered for 5.56. It would be a waste to not get the service life out of those rifles (to the military).
You can have a lightweight 7.62 rifle. Look at the AR10. But you will not be able to control full-auto fire. Now I'm just waiting for the guy, who I know will respond, that's going to say that he can fire 7.62 (I'm talking 7.62 NATO, not 7.62x39) on full auto just fine and hold his burst in a 2 foot circle at 200 yds standing. Whatever man, show me. Even if there are a few out there that could do it, that would be a very small percentage. Many new recruits don't have experiance with firearms before joining the military. I did, and thought I could shoot well but I still had to "learn" how to shoot full auto. It's much easier to train people with no experiance with the no recoil M16 than to train with a harder biting AR10. Would alot be fine with it? Yes, but not all.
One more thing to think of, while on the topic. If we went 7.62 the weapon would likely weigh at least %50 more. if that's just 4 extra pounds it sounds like small potatos. 7.62 rounds weigh in right at 3x more than 5.56. So if your carrying 300 rounds of 5.56 that equates to about 8 pounds. If you're carrying 300 rounds of 7.62 that's 21 pounds. If you think it's not a big deal then you go on a 6 hour foot patrol carrying 2 gallons of water, a flak with SAPI plates, 4 or 5 grenades of all sorts, a radio, map, compass, all serialized gear, helmet, poleless litter, AT-4s, ect. ect. ect. when it's 120 degrees.
5.56 isn't the perfect round by no means, but we have it for a reason. It does well enough. And by the way, any Marine victor unit (infantry battalion) scheduled to deploy to Iraq gets more rounds to train with than they can effectively use at times. We get quite a bit of trigger time, and I think that we can shoot pretty darn good. Does everyone learn to be a sniper at basic training? Well, no, of course. Point being, you get trigger time based on your job and deployment schedule. Why would we focus on everyone when there's only about 35% that actually patrol the mean streets. I'm not saying totally neglect all others, the insurgents might try and attack the chow hall at camp fallujah or something. Everyone should know how to basically shoot, but precedence should be given to the ones who SEEK, CLOSE WITH, AND DESTROY THE ENEMY THROUGH FIRE AND MANUEVER. Basically what I'm saying is it's the units responsibility to develope it's own shooting program. Going to the rifle range every year in not enough for infantry, but it is if you work on harriers.