A machinegun is actually a legal term, and not what we generally think of as machine gun.  The definition is actually found in Title 26, which is the tax code:
The term “machinegun” means any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The term shall also include the frame or receiver of any such weapon, any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun, and any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person.
The big problem with ATFs regulations surrounding machineguns is that the law itself sucks, so it allows the ATF to be rather arbitrary and capricious in drawing up regulations when issues come up. To me that is the heart of the problem. Any law which is defined so badly that it allows a government bureaucracy to turn people into criminals with the stroke of a pen is an unconstitutional delegation of Congress’ law making powers to the executive branch.
Big problems in this law are:
- The term “readily restored” is not clearly defined.
- By the language “any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun,” you may not be able to have any machine gun part. Even if you don’t have enough parts to make an actual machine gun.  I’ve heard of people getting in trouble for having M16 bolt carriers in their AR-15s, even though an M16 bolt carrier is insufficient to make a machinegun, because theres no auto sear in an AR-15 for the bolt carrier to trip.
- And of course “The term shall also include the frame or receiver of any such weapon” is probably where ATF’s one a machinegun always a machinegun crap came from.
If I were to rewrite this law, assuming I didn’t have the power to get rid of it entirely, I would have written it as such:
The term “machinegun” means any weapon which shoots automatically more than one shot, without manual reloading, by a single actuation of the trigger. The term shall also include any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person.
To me that language preserves the essential framework of the law, but closes the door to a lot of nonsense by the ATF.  Under this law, you could have a machine gun receiver, or a machine gun part, as long as you didn’t have all the parts you needed to make a machinegun. No more readily converted nonsense. Either you have a machinegun, have the parts, or you don’t. Pretty simple, I think.
Or this definition:
The term “machinegun” means one of many weapons suitable for use by the military, therefore being exempt from infringement of Citizen’s rights to keep and bear under the Second Amendment to the Constitution.
Hey, Law writing is fun! Maybe we should be Senators!
Umm… doesn’t that include all firearms?
It does… I think that was his point. As much as I’d love to write it that way, I don’t think any lawmakers would go for it.
First-time commenter, so a couple or three things:
1. Everybody else in the whole blogosphere puts their comments at the bottom of the entry, but no, you had to be different! Hmph.
2. “Name (required)…E-mail (required, but not displayed)…URI”
URI?
And now the actual meat of my comment (vs. the peevish snarking)
3. >>The term “machinegun†means any weapon which shoots automatically more than one shot, without manual reloading, by a single actuation of the trigger.is intended to shoot automatically more than one shot…”?
Great, no tags in the comments section. Now I really look like a total doofus–oh, hey guys…
What I meant to say was
3. >>The term “machinegun†means any weapon which shoots automatically more than one shot, without manual reloading, by a single actuation of the trigger.
You’re probably not going to convince politicians to even muck with this law at all, really. They aren’t the ones risking the ATF’s wrath, after all. I would be fine with no federal definition of machinegun, anywhere, but I was trying to come up with language that would reflect the substance of the law without being so open to creative interpretation.
The problem with just the base definition is you could, in theory, have a drop in conversion that could turn a semi-automatic firearm into an automatic firearm in a manner of seconds, and as long as you never actually used it, it would be fine. That would be fine with me, but it would be a major change in the law.
All the language in that statute was meant to cover that, but I think it goes overboard, so I was stating how it could be scaled back, but still preserve the inherent intent and impact of the law, but without being quite so open to arbitrary interpreations.