Is there a statutory difference between a flash hider and a compensator?
Doesn't appear to be. Even the BATF admits it...
This refers to your letter of January 13, 1999, in which you ask
about flash suppressors. As you are aware, the term flash
suppressor appears in the definition of a semiautomatic assault
weapon in section 921(a)(30) of Title 18, United States Code. The
term flash suppressor is not specifically defined in the statute.
A flash suppressor is a device which diminishes the visible flash
which occurs at the muzzle of a firearm as the bullet leaves the
barrel. While certain devices are exclusively designed as flash
suppressors, many other muzzle attachments are designed to perform
multiple functions such as a combination flash suppressor and
grenade launcher, or a combination flash suppressor and muzzle
break. Any such combination devices which function as a flash
suppressor would qualify as a flash suppressor for purposes of
section 921(a)(30)(B)(iv).
A firearm silencer or muffler would also function as an effective
flash suppressor; therefore, a semiautomatic rifle, such as an AR-
15, having a silencer or muffler and a pistol grip would qualify as
a semiautomatic assault weapon as that term is defined in section
921(a)(30)(B).
We trust that the foregoing has been responsive to your inquiry.
If you have further questions concerning this matter, please
contact us.
http://www.cs.cmu.edu/afs/cs/usr/wbardwel/public/nfalist/atf_letter51.txt
Given that, it would be up to the ATF firearms examiner/technical branch to test the device and determine if it reduces or minimizes the muzzle flash.
(doesn't sound very comforting... does it?
).
Typically, companies developing new or different products that might be questionable or be in a grey area, will send an example to the BATF for testing and determination (recall the 10/22 bumpfire device that was initially approved then later determined to be a full-auto conversion?)
I've seen a few ads for a manufacturers/distributors muzzle brakes with the claim "BATF approved" (or similar wording), or "awaiting BATF approval).
The grenade launcher definition is another "gotch'ya" head scratcher.
I don't recall the exact size/diameter flash suppressor/muzzle brake (might be 22mm-24mm), that the BATF has determined is capable of accepting rifle launched grenades (as if they're easily obtainable at any gun store or flea market
). Some of the dual purpose devices will have grooves/rings cut into them and either a snap ring/gasket or spring like addition to hold the grenade in place on the launcher. Not that long ago, I saw one manufacturer that was selling a US made dual-purpose muzzle device (US made to be 922r
compliant, made to resemble a grenade launcher to add authenticity to the firearm). The only difference was that there was no provision to install the retaining ring to hold the grenade properly in place on the "launcher".
I don't recall if it was submitted to the BATF to determine if it could still function as a grenade launcher or not (sounds a bit shaky to me).