You guess say no 7.62 and 5.56 interchangable.
But what if you move the magwell to the upper, then move the front lug to the lower rear of the magwell. Keep the lower the same,minus the magwell, then move the bunny ears to the lower front, like right in front of the trigger guard.
Of course, that would make the lower receiver basically be a stock and trigger group, instead of the stock, trigger group, magwell.
That means that the part that would interchange between 7.62 & 5.56 would be what? 2.5lbs?
Basically, I can see how they could get around the problem, but that PROBLEM is to a SOLUTION which was asked for by the govt to a PROBLEM that never existed in the first place.
Why do you need interchangeable calibers in a rifle anyways? I cannot imagine a circumstance in the field where it would be needed to have 7.62 and 5.56 out of one person. Just have one guy with the 7.62 and one with the 5.56