* Muzzle loading cannon – NOT, as it is an antique design, unless it has some special features allowing breech loading.
* Explosive grenade – is a DD
* Molotov cocktail – is a DD
* M-79 or M-203 40mm grenade launcher – is a DD
* Smooth bore 37mm projectile launcher – not a DD. Not even a title 1 firearm. This item falls under the "not a weapon" (signaling device) exception, I believe. Generally a large bore device for which no anti-personnel ammo has ever been made will NOT be a DD. This used to be true of the 37mm guns. However, according to ATF, some folks have started making anti-personnel rounds for these guns, and ATF has ruled that possession of a 37mm launcher and a bean bag or rubber shot or similar round is possession of a DD, and at that point the launcher needs to be registered. Put another way, before you make or buy anti-personnel rounds for your 37mm launcher, register it as a DD. The rounds themselves, not being explosive, incendiary or poison gas, are not regulated in themselves either. It is just the two together. See ATF Ruling 95-3.
* 40mm grenade for an M-79 or M-203 – a DD.
* Non-explosive 40mm practice ammo – not a DD. Commercial making of it would require a type 10 FFL though, as although the ammo is not itself classified as a DD, making ammo for a DD requires the FFL.
* Non-sporting 12 gauge shotgun – is a DD, because it has a bore over 1/2", and is not exempted unless it meets the "sporting use" test. Check out the case Gilbert Equipment Co., Inc., v. Higgins, 709 F. Supp. 1071 (D. Ala. 1989) for how the sporting use test has been re-interpreted from what it meant when the law was enacted to having ATF be arbiters of what is "sport".
* Flame Thrower – not a DD, nor even a firearm. Unregulated as to possession, under federal law. Great way to clear snow off the driveway.
* Japanese Knee Mortar – A DD. Even though there is no available ammo for it, explosive or otherwise, and hasn’t been since 1945, because anti-personnel ammo was made for it in the past, it is a weapon. As it has a bore over 1/2" and isn’t sporting, it is a DD.

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