I know this topic has been beaten to death on numerous occassions, but it always seems to remain vague. I've got 3 AMD65 kits waiting to be built, so that's why the rulings have struck my interest now.
" Firearm. (a) A shotgun having a barrel or barrels of less than 18
inches in length; (b) a weapon made from a shotgun if such weapon as
modified has an overall length of less than 26 inches or a barrel or
barrels of less than 18 inches in length; (c) a rifle having a barrel or
barrels of less than 16 inches in length; (d) a weapon made from a rifle
if such weapon as modified has an overall length of less than 26 inches
or a barrel or barrels of less than 16 inches in length; (e) any other
weapon, as defined in this subpart; (f) a machine gun; (g) a muffler or
a silencer for any firearm whether or not such firearm is included
within this definition; and (h) a destructive device. The term shall not
include an antique firearm or any device (other than a machine gun or
destructive device) which, although designed as a weapon, the Director
finds by reason of the date of its manufacture, value, design, and other
characteristics is primarily a collector's item and is not likely to be
used as a weapon. For purposes of this definition, the length of the
barrel having an integral chamber(s) on a shotgun or rifle shall be
determined by measuring the distance between the muzzle and the face of
the bolt, breech, or breech block when closed and when the shotgun or
rifle is cocked. The overall length of a weapon made from a shotgun or
rifle is the distance between the EXTREME ENDS OF THE WEAPON measured
along a line parallel to the center line of the bore."
Extreme ends should be maximum length (OAL)?