I've been everything from rifleman to acting platoon seargent in a Marine grunt unit and to answer your question xmid, I highly doubt that scenerio has or will play out with any Marine infantry units. I can't speak to recon or STA or any of those guys, but in the straight infantry units you'll used what your issued and stop asking so many fvcking questions. I haven't been to combat with the crunchies, but I really can't see any drastic changes occuring just from going in-country. The problem is not just ammo, it's all the parts of the weapon. What if a gas tube gets bent, or any other of the parts that can't be replace with M-16 parts. Also, what are they going to do with their stock upper recievers, leave them in the states, maybe throw them in a seabag. I can tell you niether of those options is going to give a CO, much less the battalion Gunner, (W-O weapons specialist) a warm fuzzy. I'm sure some swaps like you discuss have happened, but I'm 99.9% positive they were not officially sanctioned. We are talking about Marines, if they see a better solution they'll figure out a way to get what they want not matter what is officialy allowed.
That being said, thank God we are getting the M-4. I can't believe it since we just sank all that money into M-16A4s. I hope all the grunt units get these weapons. The long-range kill factor is a non-player in todays battle field. I'd like to see some numbers on how many enemies we've actually engaged past the 300 meter mark. I'd put money that the majority of our engagements have been inside 100 meters. A 550 point target capability isn't doing much good at that point. Not to mention each squad (TO) still has three weapons with an 800 meter point target capability in the SAW. Plus it's got bipods. I gaurantee a good SAW gunner can reach out and hit any target he needs to at 500-700 meters. If your engaging a soft target that far away that is carrying Eastern block family weapons, I highly doubt your SAW gunner is too busy to make the shot. It is very unlikely that your typical enemy soldier with AK derivative will be able to reach you consistently at 300 meters.
I'm excited about the M-4 because I was also a MOUT (Military Operations Urban Terrain) instructor and the M-16 is a cumbersome weapon to try to clear rooms with. Four inches doesn't sound like a lot but in a MOUT environment you often feel like a stiffy could be the difference between adequate cover and being left out in the open.
I was going to stop my rant there but then I remebered FlyNavy mentioning the fragmentation ability of the round. The penetrating power of our weapons versus the Eastern block family of weapons is truely scary. In TBS they showed us video of ballistic tests of the different types of weapons. The AK-47 round went through a ciderblock wall, through a metal filing cabinet, through a dummy wearing a flack jacket and out the wooden back wall. It also went through a brick wall, all the other stuff but lodged in the back wall. The M-16 took something like 15 rounds fired in the exact same point (weapon was mounted) to get any penetration through cinder block. Even the 240G (7.62mm) took five round to penetrate the cinderblock wall and took 15 to penetrate the brick. They tried to sell this to us as an advatage because we didn't have to worry as much about collateral damage but I say BS. If I'm in a firefight my main concern is getting as many hot pieces of lead as possible into the other guys body as quickly as possible. Long story short (too late) I agree that the 5.56 may not have been the ideal choice. In a day and age when we're dropping hellfires, TOWs, JDAMs and abunch of other munitions that cost hundreds of thousands of dollars a piece would it really be so outragous to completely revamp the shoulder fired weapons that our young men go into harms way with every single day?
