Well, let’s be careful here: I’m pointing out the 6.5x284 only as evidence of the superior exterior ballistics of the 6.5mm bullets.
The Winchester .284 is a real oddball case, a “rebated rim” case, which means that they’ve using a .473” head, but the case diameter is large than the head rim.
For a full-auto weapon, there are feeding issues that have to come into consideration of the case design, which is why I say “start with the bullet” and then design a case that will feed properly, then start worrying about the action. The superior ballistics mean nothing if our guys are dying because their rifles jam, much as the superior accuracy of the M-16’s direct gas impingement means nothing if the action fouls and jams or fails to feed.
The whole method by which we now field weapons is infuriating to this taxpayer. Colt is taking some serious money off the US taxpayer at the same time they’re delivering an inferior product. They do this by gaming the contract bidding process.
Weapon acquisition not always logical, eh?
They did it once, starting with the gun and building a plane around it. Turned out rather successfully.