I'll plow through the GCA(1968) and NFA(1934) and see if there is specific criteria as to what "fixed" ammuntion may or may not be.BATFE is a funny agency.During the 1994-2004 AWB era,I saw many many violations of "pre-ban" configuration longguns,nobody got busted or even a good earchewing by Batman.I do know of cases that were posted on BATFEs web site for the same offense but these were people that were drug dealers and the extra charges were added.
BATFE allows semi-auto versions of 1919a4s,RPDs,MG34/42sand others,but reclassified the Gilberts USAS12,Streetsweeper/Stiker shotguns as Destructives devices subject to the NFA.They are a most illogical agency,but unfortunately make the rules(law),Congress gave them this power in 1968(I thought only Congress could make law???)
Per BATFE FAQ section:
(A5) What kinds of ammunition are covered by the GCA? [Back]
Ammunition includes cartridge cases, primers, bullets or propellant powder designed for use in any firearm other than an antique firearm. Items
NOT covered include blank ammunition, tear gas ammunition, pellets and nonmetallic shotgun hulls without primers.
Generally, no records are required for ammunition transactions. However, information about the disposition of armor piercing ammunition is
required to be entered into a record by importers, manufacturers, and collectors. A license is not required for dealers in ammunition only. [18 U. S. C. 921( a)( 17) and 922( b)( 5), 27 CFR 178.11]
(M28) Are muzzleloading cannons classified as destructive devices? [Back]
Generally, no. Muzzleloading cannons not capable of firing fixed ammunition and manufactured in or before 1898 and replicas thereof are antiques and not subject to the provisions of either the GCA or the NFA. [26 U. S. C. 5845, 27 CFR 179.11]
FURTHER INTERESTING LANGUAGE THAT MAY APPLY:
(A29) Are "potato guns" or "spud guns" legal? [Back]
"Potato guns" or "spud guns" generally consist of sections of PVC plastic tubing and fittings and are designed to launch a muzzle-loaded potato (or other similar-size projectile) using hair spray or other aerosol vapor as a propellant. The propellant is ignited by means of a barbecue grill igniter or other similar ignition system.
Section 5845(f), Title 26, United States Code, regulates certain weapons as "destructive devices" which are subject to the registration and tax provisions of the National Firearms Act (NFA). Section 5845(f)(2) includes within the definition of "destructive device" any type of weapon which will or may be readily converted to expel a projectile by the action of an explosive or other propellant, the barrel of which has a bore of more than one-half inch in diameter. However, section 5845(f)(3) excludes from the definition of "destructive device" any device which is neither designed or redesigned for use as a weapon and any device, although originally designed for use as a weapon, which is redesigned for use as a signaling, pyrotechnic, line throwing, safety, or similar device. The definition of "destructive device" in the Gun Control Act (GCA), 18 U.S.C. Chapter 44, is identical to that in the NFA.
ATF has previously examined "potato guns" or "spud guns" as described above and has generally determined that such devices using potatoes as projectiles and used solely for recreational purposes are not weapons and do not meet the definition of "firearm" or "destructive device" in either the NFA or GCA. However, ATF has classified such devices as "firearms" and "destructive devices" if their design, construction, ammunition, actual use, or intended use indicate that they are weapons. For example, ATF has classified such devices as "firearms" and "destructive devices" if they are designed and used to expel flaming tennis balls.
Possession and use of "potato guns" or "spud guns" may be restricted under State laws and local ordinances. Further, any person intending to make, use, or transfer any such device must be aware that they have a potential for causing serious injury or damage
http://www.atf.gov/firearms/faq/index.htm
