According to 18 U.S.C. 921(a)(24):
The terms “firearm silencer” and “firearm muffler” mean any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for use in assembling or fabricating a firearm silencer or firearm muffler, and any part intended only for use in such assembly or fabrication.
According to this ATF ruling, even if a device was not intended to "silence, muffle, or diminish the report of a portable firearm," when it becomes readily usable for that purpose, it is a sound suppressor under the above US Code. The device in question was a paintball gun "suppressor" that reduced the sound of a .22 by under 8 decibels.
No definition of actual sound reduction required to be considered illegal was given in the ruling. Therefore, we may assume that any device capable of reducing sound by even a single decibel is illegal. There are no allowances for devices that were not ostensibly intended to reduce the report of a firearm, but do so as a consequence of their design.
Unfortunately for owners of (a certain muzzle brake) such as myself, in my recent testing, it proved to be one decibel quieter than the same weapon without a muzzle device (This is in line with other informal testing that I have seen conducted by people such as myself - however, it is more offensive to the ears of some people because of the frequency of the report, not because of the number of decibels emitted).
Were I to continue using this device, knowing that it apparently diminishes the report of a firearm, it would seem that I would be committing a felony.
I must make it clear that I will continue to use this device and that this post was created solely to point out the ridiculousness of what is apparently interpreted to constitute a "silencer" under 18 U.S.C. 921(a)(24). See this page for information on a related topic, although the following would seem to indicate that since the brake does not have any of the following features, it would generally not be considered a silencer on its own:
General characteristics of known firearm silencers include:
1 Ported inner tube (bleed holes)
2 Expansion chambers
3 Baffles or washers which create seperate expansion chambers
4 sound dampening material such as foam, steel wool and other materials
5 End Caps
A full report (and comparison with Spikes 11.5) will be forthcoming. The Vltor A5 stock system was used for this video.
Anyone who is familiar with the Century Arms "Tantal" 5.45x39mm AKs has probably heard that some of them had issues with keyholing. That is, the projectiles would impact their target at an angle, leaving a "keyhole" impression instead of a round hole. I owned a Century Tantal, and while I had several complaints about the weapon, it did not keyhole when I put Russian surplus ammunition through it - though the person I sold it to did have such problems.
It was widely accepted that the cause of this was the use of barrel blanks that were originally intended for use with .224" diameter projectiles. These barrels weren't able to stabilize the .221" diameter 5.45 projectiles.
Recently, I loaded some 60gr Hornady 5.45 projectiles in 5.56 cases. I fired them through a 5.56mm AR-15 with a 1/7 twist barrel at a target 50 yards distant. Not only did they not keyhole, they actually kept a pretty tight group considering the factors involved (shooter stance, optic, etc). I'm going to do more testing, but it appears that the simple explanation of "5.56 barrels won't stabilize 5.45 projectiles" isn't entirely true.
Also, I've been loaned a few more weapons for review by a generous benefactor - a Sig P226 X-Five Tactical, an FN FNP-45, and a Sig 556 Pistol. They'll be reviewed shortly.
Because the District of Columbia continues to enforce unconstitutional restrictions on the right to keep and bear arms, despite the 2008 Heller v. DC Supreme Court ruling, a "Heller II" brief has been filed, challenging the restriction on what DC calls "assault weapons" and bans on weapons that can take magazines holding more than 10 rounds.
Although a certain number of justices will certainly allow personal bias to override what should be a clear decision, I have faith that this legal attempt will be successful, just as Heller and McDonald were.