fictitious war...pick your arms

[stanc]

I saw the OP's choice of "fictitious" as the great escape from that mindset, which has marooned us in the 20th Century...

I guess you missed the part where he said, "you may choose between the ar-15 and ar10 platforms."

One need only visit the movies to get a glimpse of future weapons design...

Not exactly. The guns that one sees in the movies are, at best, what the designer imagines that future weapons might look like, not necessarily what they will look like.

(That could possibly be an interesting project: Look at movies of decades past and see how their concepts of early 21st century military weapons compare to what is actually in service.)

We've come a long way in the recognition that shorter, more compact is better.

Indeed. And yet, the US Army still shows no interest in the bullpup configuration (for rifles). Note that the new Compact Semi-Auto Sniper System is an AR10 variant.

Plus, New Zealand recently decided to replace the AUG bullpup with an AR15 variant.