IANAL, but mere possession of an automatic weapon is prohibited, is it not?
I thought the idea behind the receiver for the AR15 is that with a slightly different receiver that the AR15 becomes an automatic weapon (aka. an M16)? Or are we talking about the semi-auto (AR15) receiver?
The receiver doesn't make any difference at all whether it's full auto. Or rather, the legally designated lower receiver contains the firing mechanism (which can be full or semi auto), but the receiver itself is just a piece of steel and you can change out the actual mechanism.
Not entirely accurate. The ATF actually specifically requires that semi-auto weapons are not readily convertible to fully automatic by way of a simple parts swap.
A standard, semi-automatic AR-15 will not accept a full-auto M16 trigger group; the M16 trigger group requires an extra hole to be milled in the receiver which isn't present on semi-auto receivers.
The lower receiver doesn't determine if it is automatic or semi-automatic. That's the upper receiver.
And automatic weapons are regulated in the U.S., they are not prohibited (everywhere, anyway). If you go through the appropriate paperwork (and a few months wait), and live in the appropriate places (Louisiana, etc.), you too can own a (pre-May 1986) fully automatic weapon.
Don't know about the legality, but you're correct about the reality. There are number sliding and rotating parts in the lower receiver that determine whether it fires single shot, burst or fully automatic. Modern M-16s have single shot and 3 round burst. The original 70s model had single shot and full auto.
