It depends on the exact specifications, but it may either be Section 1 (requires an FAC), Section 2 (requires an SGC) or Section 5 (essentially completely illegal).

Ishouldn't think for one second that SKY got dispensations for their project. They have highly qualified researchers and lawyers to advise on their projects. I'll bet it was on private land, with the owner's consent and a million miles from a public highway. According to the NFA and GCA previously mentioned, it must be muzzle loaded, not rifled, or use any projectile which is intended to be used as a weapon. Any device using compressed air would be completely exempt from both. Although spudguns are created and used for the purpose of recreation there are other devices which work on identical principles in many other fields with more serious uses. Pierson, Hazel M.; Price, Douglas M. (Spring 2005). "The Potato Cannon: Determination of Combustion Principles for Engineering Freshmen" (PDF). Chemical Engineering Education. 39 (2): 156–159 . Retrieved 15 August 2011. [ permanent dead link]The range of pneumatic cannons is more variable than the range of combustion spud guns due to the increased variation possible in the components. Typical ranges are slightly higher because of the greater power, but the maximum range of some high power pneumatic cannons has been said to be over 1,000 metres (1,100yd). [9] In spite of what you say about your land being in the middle of nowhere, someone will own it and someone will have access rights to it although,I admit, maybe not the public. Perhaps you can get the landowner's permission to fire your cannon on it. Even then you have a duty of care to ensure there are no third party injuries or damage. Someone (and you admit it may be you) will inevitably get hurt.

Golf ball launchers: at some charity outings players can make a donation and launch a golf ball over 300 yards and use that as their tee shot. Usually the vendor hired by the event organizer launches the ball for safety and liability reasons. Any pneumatic with a potential power output exceeding 12 ft-lbs will also fit within either section 1 or section 5 (Section 2 cannot be air powered)Promotional sports cannons: Portable pneumatic cannons which run on bottled CO 2 are common at large sports games in the U.S. where they are used to project items such as T-shirts or wrapped food into the audience. Such cannons can be dangerous: the Phillie Phanatic injured a fan with a hot dog cannon in June 2018. [24] Such "air cannons", as they are often called, tend to be made of higher-quality materials than an average pneumatic spudgun, but they use the same methods of operation.

Barker-Griffith, Ann E.; Streeten, Barbara W.; Abraham, Jerrold L.; Schaefer, Daniel P.; Norton, Sylvia W. (1 March 1998). "Potato gun ocular injury". Ophthalmology. 105 (3): 535–538. doi: 10.1016/S0161-6420(98)93039-1. PMID 9499787 . Retrieved 15 August 2011. I have heard of people being given clips on the ear for it, and even some cases of the armed response unit being called, which may well have included arrests, but bear in mind, that relates just to people I've spoken to on the internet - a very small minority, and generally a more sensible one, and if even they can get the ARU on them... psycix wrote:Though Ragnarok may go explain the UK laws regarding silencers now, im not sure about their legality.Brass: Often brass fittings are used on spud guns for small parts of the construction like fuel systems, because it is one of the most common materials for small pipe fittings. Occasionally large parts of spud guns are machined entirely out of brass. [14]

Van Horn, Dale R. (October 1932). "Perform These STARTLING STUNTS with DRY ICE". Modern Mechanix and Inventions: 114–116 . Retrieved 15 August 2011. I have one but I am not sure how legal it is. How can it be legal to own a 12ft/lb air rifle but not a potato gun. The ATF has previously examined potato guns or spud guns as devices using potatoes as projectiles and used solely for recreational purposes, do not meet the criteria of a destructive device defined by the National Firearms Act, or the Gun Control Act. They have however classified said guns as destructive devices when they used incendiary tennis balls.How the Humble Potato Cannon Served the Allies in World War Two Popular Mechanics, Retrieved April 4, 2017. Pneumatic launchers [ edit ] A large pneumatic design: The projectile is loaded in the muzzle (not pictured), which is then attached to the cannon (at 2). The air reservoir (3) is filled to 120psi (0.83MPa) using the Schrader valve (4). Upon opening the solenoid valve (1), the air from the reservoir is transferred to the projectile, which is fired out of the muzzle. These blue soft darts can be used with all soft dart guns. You will receive 30 x Blue Soft Darts... A MythBusters episode tested a potato cannon held together by duct tape compared to one held together using PVC bonding agent. Another episode, testing MacGyver myths, supplied Adam and Jamie with the materials to build a potato cannon as part of a challenge to "MacGyver" up a way to signal a rescue helicopter; however, they used the piping and other supplies present to build a large kite instead. Ayars, Eric; Bucholtz, Louis (July 2004). "Analysis of the vacuum cannon". American Journal of Physics. 72 (7): 961–963. Bibcode: 2004AmJPh..72..961A. doi: 10.1119/1.1710063 . Retrieved 15 August 2011.