@Aaron Fox
What new ground did the OICW tread, in your opinion?
EDIT: As far as I can tell, most of what it did was integrate a grenade launcher, rifle, and scope... and fail to replace the M4.
The biggest new ground it broke was sensor-fused High-Low grenades with the sensor integration being the second biggest new ground it broke (the scope was more than a simple scope, but more akin to a sensor array with integrated fire control systems and a fire control
microcomputer that happened to have an optic sight... think what Mass Effect small arms are
fluffed to be and not what they're displayed in gameplay and you wouldn't be far off), but a lot of the problem with the OICW was that 1) sensor fuse technology wasn't
there yet (especially at 25mm caliber, right now 30mm is the smallest without sacrificing lethality too much), 2) the miniaturization of various sensor components for the scope assembly wasn't as easy as once thought (for the time), 3) the switch from a PDW caliber weapon (the original concept -from what I understand- had the MP7 as the kinetic weapon system) to an assault rifle weapon really screwed things up. You must note that this is based on rather hard data showing that it isn't small arms that did the majority of the killing but
explosives, be 40mm High-Low grenades to 500-pound bombs and beyond. The OICW's sensor fused grenade was to 1) maximize lethality while 2) minimizing collateral damage. So the idea was that, since small arms provided the least kills, give everyone a grenade launcher that does most of the work for them, thus vastly improving the firepower and thus
survivability of the US soldier.
However, the idea of the OICW is more viable now than ever, surprisingly enough, given the advent of Metal Storm technology and advancements in sensor, sensor fuse, fire control, and computer miniaturization. One of the last things that Metal Storm produced was the 3GL system, which is a 40mm caseless stacked grenade launcher. Last I've checked, each 40mm round that the 3GL uses is lighter than the High-Low 40mm that the military uses.
An artist's rendition of how it would look like including ammunition:
The artist did a rendition of interestingly ingenious use of the 3GL style launcher for the OICW concept, but that is sadly lost to the internet after the artist vanished. I was only lucky enough to only a handful of these still around myself (and the grenade launcher above is one of those that I had to save and put into my Deviantart stash).