We all have them or at least have seen them. Those cute little International orange or yellow plastic flare guns with their abbreviated 12-gauge rocket flares. They run about $50 for a new one. There has long been a desire to turn them into...something more.
26.5mm European Projectors
These flare guns are popular with foreign militaria collectors. They are lore bore (slightly over one-inch wide) projectors used by many Western European military units and merchant shipping/SOLAS purposes. These flare guns are available in the US in surplus condition anywhere from $70-$200 depending on their background. Newer versions are mainly plastic and aluminum while older WWII era pieces can be quite nice and made of steel.
The Florida-based Kennesaw Cannon Company is currently manufacturing and selling two different sub-caliber devices for these projectors. One, in .22 LR retails for about $30. The other, in .410/.45LC for about $60. The interesting thing with the.22 sleeve is that it will accommodate .22BB, .22CB, .22 Short, .22 Long, and .22LR.
These are both currently BATF approved. Installation is easy, simply slide this insert into your flare gun and you're done. The rifled steel barrel is encased in a lightweight corrosion resistant adapter adding minimal additional weight. This is a perfect idea for a survival kit, especially for a hiker, or in a boat or airplane.
Reviews of the 22LR are mixed and it’s been reported that spent cases bulge a bit, and require a cleaning rod or other metal rod to push them out of the chamber of the sub caliber insert. (Kinda like the old Liberator 45 single shot.) This does not seem to be a problem with the .410/45LC version.
12Gauge plastic flare gun inserts
A few years ago there were a number of insert devices, constructed of 6061 aluminum, that were advertised as converting a 12 Gauge plastic flare gun to a single shot 38 Special. Upon independent testing, the ATF's Firearm Testing Bureau noted that "The live fire testing resulted in the eventual destruction of all four flare launchers, and confirmed that the use of these adapters in conjunction with conventional ammunition is likely to result in a catastrophic failure of the flare launcher."
Similar tests with the same type of insert that sleeved down an Orion 25mm flare gun to accept a 12-gauge shotgun shell brought the same result. Remember, flares are low-pressure rounds (ever felt a flare gun recoil?) and you should remember that for safety's sake.
Any Other Weapon?
Be extremely careful when buying and installing any of these inserts due to a little known clause in the National Firearms Act concerning "AOWs". An AOW is “Any Other Weapon,” which is a firearm subject to the provisions of the National Firearms Act (NFA).
26 U.S.C. § 5861(d) states that it is unlawful to receive or possess an NFA firearm which is not registered in the National Firearms Registration and Transfer Record. Violation of the cited section by an individual is a felony subject to a maximum penalty of 5 years imprisonment and/or a fine of $250,000. In the case of a violation by an organization, the maximum penalty is a $500,000 fine. In addition, 18 U.S.C. § 2 provides that a person who knowingly aids and abets another person in the commission of an offense is also responsible for the offense. Thus, the sale of components in violation of § 5861(d) may place the seller in violation of 18 U.S.C. § 2, as well.
In short, if you buy an insert and use it for your own personal use, that’s ok under the current law. However if you go to sell it (along with the flare gun) it is a non-registered firearm and can get you in hot water. You could have a pretty big criminal liability down the line if you cross the line on a NFA violation. (The foregoing not to be taken as legal advice, check both federal law and laws in your particular State of residence.)