The rear mag is for 20mm HE(high explosive) rounds that have a time fuze which is set via laser rangefinder. The potential for that, if it works, is astounding. It's meant to kill soldiers by exploding above them in foxholes (term for that is "In trench line") or around corners.

Another neat thing is that the OICW is integral to the Army's FORCE XXI vision, which involves availability of real-time battlefield intelligence to every level of the maneuver and command forces. Even though night vision devices look cool, FORCE XXI suggestions make them look pointless. The top scope on the OICW is an IR camera that can be tapped to a display mounted on the helmet over one of the soldier's eyes. Current M-16/M-4's do sometimes have an IR sight, but rarely for regular grunts. They're huge, and I still have yet to see a gun camera / helmet link for real hwoever in the world of Halo potential for a HUD to be superimposed on the Soldier's visors would allow for such a device...

Image from Security Arms.

It's also interesting to note that the Halo team opted for standard ammo as opposed to caseless munitions.

Heckler and Koch designed a caseless assualt rifle in the late 80's called the G11. Caseless ammo is lighter, more compact, more accurate and is less wasteful than conventional bullets. I guess caseless weapon are slightly less Hollywood though than most people's impressions of a gun fight...hell I even gotta confess to turning on shell casings in Quake 3 as soon as that became an option ^_^

Here's an interesting article on the G-11 and caseless ammo systems.

It will be interesting to see if Bungie allows us to customize the type of rifle, grenade ammo for different situations. SLAP* rounds for all out firefights and Green tips* or flechettes for armor penetration specific targets...

Covenant armor seems to be a skin tight bio-mechanical suit or a series of implants and cybernetically replaced limbs, it's pretty hard to say for sure based on the images we've seen. Enemy armor will play a big role in the importance of putting rounds into vulnerable areas if they choose to do locale specific damage.

About the human soldiers, all I can deduce so far is they're certainly loaded for bear ^-^

Shoulder mounted lights, lots of body armor and bandoliers, should be interesting to go for a drive in the country in that jeep too.

Speaking of the jeep I'm guessing that's a .50 caliber mounted on the back. From some of the closeups on halo.bungie.com/ though I can't tell where the ammo feeds.

Any thoughts or further insights are welcome. I'll delve into the sub-machine gun and pistol next...Sicne this game is guerilla warfare it might be nice if they include some suppressors with some of the weapons ^-^

SLAP: Standard Light Anti-Personel
Green Tips: Rounds with a tungsten carbide penetrator at the tip.