How does that definition coexist with the common groupings of high explosives (detonates, nitroglycerin) and low explosives (deflagrates, smokeless powder)?
Wait a second. Does this mean that any weapon that has a barrel with a bore of less than a half-inch in diameter does not qualify as a destructive device? Sounds like they’re perfectly willing to listen to Reason…
The definition santo rugger is correct by not universal depending on area being discussed. “Energetics consist of explosives, pyrotechnics, and propellants”. A spot you’ll find this definition is in TM 9-1300-214, Military Explosives.
Transportation and storage - wise; explosive definition is anything [substance, article, or device] that functions by explosion (i.e., an extremely rapid release of gas and heat) or which, by chemical reaction within itself, is able to function in a similar manner even if not designed to. This includes pyrotechnic substances. Your explosives and explosive devices are in Class 1 with six divisions based on the principal hazard from an incident. A compatibility group letter is also assigned to further breakdown the hazard (this takes into account initiation potential, physical characteristics of device, packaging, safety devices, multiple components, additional hazardous materials present, etc…). This comes from CFR (Code of Federal Regulations) 49, Subpart C 173.50 and other sections dealing with air, vehicle, and rail.
You have DOT groupings; Class A, Class B, and Class C explosives related to the hazard of the items. Generally Class A explosives are Hazard Class/Division 1.1, 1.2, 1.5, and 1.6 (detonation hazard commonly called High Explosives). Class B explosives are generally HCD 1.3 (usually the propellants, propellant loaded devices, and large pyrotechnics called Low Explosives), and Class C explosives are HCD 1.4 (usually small propellant devices and small arms ammunition and components). Note the liberal use of “generally” and “usually”.
Your division of high vs. low explosives divided by the rate of decomposition into deflagrate and detonate is used in military terminology and instruction as well. The rate of decomposition determines the split. Detonation is decomposition at rates faster than the speed of sound which proceed through the substance. Materials which detonate are your high explosives (TNT, PETN, RDX, etc…). When decomposition is slower than the speed of sound, it’s deflagration. Also the reaction proceeds only at the surface of the material. These are low explosives; typically propellants, black powder, most pyrotechnics.
Classification complications arise from characteristics like density, configuration, shape, degree of confinement, ambient temperature, physical state, physical dimensions, means of initiation, and others. An example is TNT. Considered a high explosive in most uses; it will only deflagrate (burn) if initiated in a loose state not packed too densely, not too deep, over a small surface area, by a flame. Some propellants are classed as high explosives. Some pyrotechnic compositions always detonate versus deflagrate. Lots of special cases.
Maybe next year after retirement I’ll do an “Ask the ammo guy” thread about military ammunition and explosives.
I’m confused: if you have a blast, isn’t technically a firearm? 
What smithsb said, especially this:
The detonation velocity (speed at which the detonation front propagates), power (most importantly detonation pressure), brisance (shattering effect) are all considered. As smithsb pointed out, it depends on the configuration; the distinction is made for the general case.
High explosives are also divided into primary, secondary, and tertiary. Primary are extremely easy to set off (i.e. the primer of a cartridge), secondary explosives (usually) require a primary to initiate detonation (dynamite, TNT, C-4, etc.), and tertiary require a secondary to ignite them (ANFO). Tertiary are usually used in mining, because they’re cheap per unit energy. Primary explosives are relatively weak, and are generally only used as detonators.
As smithsb said, given the right conditions one can force an explosive to deflagrate or force a pyrotechnic to explode (conditions include the ones he listed: confinement, shape, temperature, etc.).
Bear in mind, just because something isn’t legally considered a “firearm” or a “destructive device” doesn’t mean it’s not considered a weapon. Being allowed to own something doesn’t mean you can carry it around with you in public - for instance NH allows you to own, but not carry, certain types of knives. I can walk down my street openly carrying a machine gun - but not a dagger. (Hmmm, do bayonets count as daggers?)
I think legally the firearm litmus test would constitute muzzle energy.
A railgun has record levels of muzzle energy, currently constituting 10 megajoules… soon to be ramped up.
If it has a muzzle and energy then I think it is a firing arm.
I’m new here, this is my first post, i’m digging up an old thread, but i can clear up some myths (maybe).
Well i’ve been hunting up and down the net with the same intentions as the OP…
I’ve got the intentions to R&D some coilguns, but have no idea on their legality.
I live in Australia, and well, now i know… As do any Australian users.
So i looked up the Weapons Act and fount this:
So this raises questions: It states that an electromagnetic weapon is one that uses EM to DIRECTLY damage the target, but not one that uses EM to accellerate a projectile?
Even then i can conclude that coilguns ARE ILLEGAL in Australia, as the law is thorough enough to instate that ANY item which can accelerate a projectile is a weapon.
But that’s just the law, in writ.
A judge in court will most probably laugh at the coilgun and it’s creator, and slap with a fine and confiscate the coilgun…
Plus, unless waving the coilgun about like a douche, nobody will find or even KNOW about it if your’e responsible, and add the benefit that coilguns are silent, so testing them is no problem.
PatriotGrrrl, Bayonets count as Daggers. At least according to the Weapons Act…
TV Tropes call this oneCut Lex Luthor a Check.
And, just for fun, here is the science fair project scene from Joan of Arcadia, where the rail gun… goes off the rails.
I’m not sure what the OP is referring too. There is a bolt gun used to put down injured horses or livestock. Vets often carry them. It fires a metal bolt that enters the horse’s skull and then retracts back into the gun.
http://www.fao.org/docrep/003/x6909e/x6909e1i.jpg
http://www.livestockhealthsystems.com/Blitz.html
It could kill a human if you could get them to stand still. 
It has to be held directly on the forehead. The bolt only extends out a couple inches.
I think they are considered guns and regulated like any gun. Some don’t look much like a gun. They are just round like a big pipe.
The advantage to a bolt gun is safety. They can be used in barns, stockpens and farms without fear of a stray bullet hitting anybody.
Heads or tails?, friendo.
AFAIK there no such thing as a man-portable version of either one. And they are pretty much completely unlike a bolt gun (many orders of magnitude difference in destructive power).
The real question is, can they kill zombies?
No that is incorrect, thewre is no such thing as a “class 2 Liscense” You need a type 7 standard FFL. And as long as you aren’t manufacturing for sale you can build whatever the hell you want. Actual firearms need only be of legal proportions. Shotguns 18 inch barrel, 26 inch Overall length. Rifles 16 inches and agains an OAL of 26 inches. Any shorter and you’ve manufactured an SBS/SBR And are subject to the National Firearms Act. Please in the future remember to do your research.
You can make a railgun in pretty much any size. A man-portable railgun wouldn’t be very practical, but then, the larger ones aren’t very practical, either.
The definitions in an Act are for the purposes of that act.
Another act may import the definition, “As defined in Section 3 part 2 of <act>”.
Or “if then” it based on the act ". “if section 3 part 2 applies to the device of <act>, then it is a gun”. That sort of import…
But its not to be treated as english language definition.
What I think the Weapons Act 1999 is , is the Western Australia state law that moves the use of higher powered rifles and machine guns into the Weapons Act. The prohibited ones would be Machine Guns and full auto “assault rifle” and controlled ones might include all lesser rifles - for example.
So the point is that it moved higher powered guns from “guns act” to “weapons act”. It meant that the higher powered guns are called weapons and that the weapons act applied to them. ( It doesn’t mean to say that that the higher powered guns are not in the english language meaning of “Gun” … just that you use Weapons Act not Firearms Act for guns in the Weapons Act prohibitions and controls. Worse is that the WA Weapons Act doesn’t define the weapons, it leaves that to regulation, which the minister can modify in a moment tomorrow.
So you cause a problem with your rail gun, eg demo it in a park, and the minister makes it illegal in 5 minutes.
Canada also has a law against “possession of a dangerous weapon”. AFAIK it covers just about everything - you can even get this charge if you have a hockey stick or baseball bat and threaten to use it in a dangerous manner. I suppose a real lawyer can pipe up, but it seems to me that possessing something that has no practical use other than as a dangerous weapon obviates the need for the prosecutor to show intent to use as a weapon?
Most states have adopted the federal definition of firearm, which is the same one cited by Scumpup above (though his link no longer works). The language is taken from 18 U.S.C. § 921. Most states (and the feds) do not define the term “gun.”
In Florida, a railgun would presumably come in under the definition of an “electric weapon or device,” which means:
[QUOTE=§ 790.001(14), Fla. Stat.]
[A]ny device which, through the application or use of electrical current, is designed, redesigned, used, or intended to be used for offensive or defensive purposes, the destruction of life, or the infliction of injury.
[/QUOTE]
You need a class II license to sell a firearm you made. There are no licensing requirements on home made guns (they don’t even need a serial number) .
A non-licensed person may make a firearm, provided it is not for sale and the maker is not otherwise prohibited from possessing firearms (such as a convicted felon). (18 U.S.C., Chapter 44; § 922 (d).) Federal law imposes none of the same restrictions on non-licensed possessors, and as a result, homemade guns need not be registered and the owner need not undergo a background check.