Again... I'm going to the Hangun section to start a 9mm vs. 45acp debate.
Something not addressed, for every 1 grunt there's about 4 not infantry MOS's. The M14 is heavy, and that big .30 round isn't needed in a weapon that doesn't see any combat, that's just there for personal security and a show of force. There are alot of service personel that don't fire a single round outside the wire in Iraq, there are many that leave the wire that don't fire more than 30 rounds for thier whole tour in Iraq. The War fare in Iraq is different from anything ever seen in the last 60 years, Afganistan is a wide open country of brush and mountains. A M14 may be a better choice over there, but it isn't practicle to have one unit out fitted with M14's and another with M16's. We train with M16 out of boot camp, we train with them for predeployment, there are few service personel that can shoot an M16 to it's capablitys, M16A4's will reach out to 800m with ACOGS highly acurately.
The M24 and M40 Sniper rifles earn thier keep, and from what I'm told a sniper rifle w/o scope costs the USMC about $700 in parts, not to include the armorers labor, if that armorer lives in the barraks and eats in the chow hall, that's one cheap sub MOA rifle. The .308 isn't going any were. Fallujah in April of 2004 is the only time our squads DMR came out of its Pelican Case, for all of about 3 days, it's too heavy, too bulky and too fragile for an Infantry or Engineer squad to be out humping around. There are M14's mixed into the units, M21's and M25's are in use, just not as much as the M16 but they are out there and they serve there purpose as 'special purpose' weapons, not as 'general purpose', like the M16's.
The war we're faceing now... the enemy is ununiformed and it's a war of quick manuver, with little cover at times. It's a land of keeping boots on the deck, patroling the city and rural area, it's a land of convoy operations and supply routes. The M16 is the most versitile weapon in the US arsenal, 9mm Sub-Calibers, M16A4's with ACOGS that will reach out to 800 meters, M16M4/M16M41 Carbines for raids and true urban war fare weapons. The M16 has the advantage of allowing quick follow up shots, even though it won't shoot through trees (which there aren't many trees in down town Bagdad to take cover behind). The M16 is light, the ammo is light. In a good fire fight, a Soldier or Marine can fire several hundred rounds acurately, w/o being beaten up by his rifle. The M14 is a shoulder killer, just like the M1. One shot-One Kill is a fantacy of open land battle, (go back to Bellawood), in an urban enviroment you may need to keep supressive fire going long enough to get a man in close enough with a M203 or M79 to fire a gernade into the room, cause you're little buddy up there shooting at you isn't going to just pop up for you to get a shot on him, light supresive fire that won't tear through the mud hut walls into the school next door (oh there's a plus to the 5.56mm ability not to penitrate?).
When it comes down to weight advantage, you can't beat the little M16 with 5.56mm. We have up gunned trucks and mechanized patroling to haul around our 240G, M2's and MK19's along with our TOW's. What the guys on the ground need is light weight and manuverability, that's what tracer rounds and smoke are for, to mark the target and dirrect the heavier guns. We're not shooting through jungle foliage, we're not shooting out past 300m in most cases, most of the 500+meter shots I've seen were out of true boardom, shooting armed Fallujah-ians at 800m, while waiting for the word to move in.
The stuff my squad would wear and haul around when I was in Iraq and was pretty standard over 2 tours; M16A4, double combat load, ACOGS, 2-M67 hand gernades, 1-red smoke, 1-green smoke, 2-pop up flares, Flak with E-sappi plates, Side Sappi plates, deltoid protectors, Kevlar, IFAK first aid kit and suplimental first aid kit, Intersquad radios, 2-AN/PSS-14's, Camel back, chow, assult pack and butt pack, knife of some sort, gerber, 3-M203 per squad and combat load of 18-40mm HEDP, 3-M79 with 18-40mm, 500 rounds of linked 5.56mm to the A/SAW and rifleman, have 1-PRC119 per squad, VHF radio, 2-M1014 Benelli shot guns and rounds, 3-SAW's with 800 rounds linked, 1-10lb sledge, 1-hooligan tool, C-4, det cord, electric and non/electric caps, M60 ignighters, maps, pens, flashlights, batteries of 3 differnt types, cem lights, IR cem lights, M9 and 60 rounds if you're lucky... then there's toys and candy for the kids too, don't forget that. Spread load all this crap over a 13 man squad, plus a radio man, plus a Corpsman... you get some pretty hard men, that eventually end up with joint problems and exhaustion after a few days outside the wire. The strap this crap on thier backs for 7 month rotations, then come back home for a few months and start back into build ups to be back in Iraq about the same time they left the year before, and people wonder why the military retention rate sucks.
I'm out of the Engineer MOS at the moment, but you want us to patrol with heavier rifles on top of all that stuff too... how are you going to put a M203 on a M14? Cause I'm not giveing them up, even with haveing M79's back in the USMC armorys now. How long is it going to take to train us up on the M14? How? are you going to put picitinny rails, Pac-4's, surefires and all the other crap we have, ergonomicly and comfortable? You aren't, sorry.
The M14 served it's purpose; but the current war is all about; high-speed/low-drag and light loads, we need a weapon that can get us back on target quickly and that requires minimal recoil. The M16 and it's variants are purposely serveing. It doesn't take that much to keep a M16 running smothly, just a bit of respect for the mechanics that your life depends on.
I really don't know why everyone has such a distain for the M16? It's a killing machine, sure it could use a bit more knock down power, but it works.
Dirrections for 3-round burst (when fired correctly it's great), aim for the crotch, squeze 1 time, 3 rounds go out, walk up to hodji you were aiming at, you find one in the crotch, one in the gut and one in the chest, 3 little pencil holes... alot easier than trying to shoot controled pairs. After 72 hours out side the wire, you start looking for simple ways to do things effectively.