I would be very careful about what you stick on the end of your post-ban barrel. Some companies, such as SOG Amory, advertise a 'Post-Ban Legal Flash Hider/Compensator'. The ATF ruled that any muzzle break or compensator, etc., that also acts partially as a flash hider is in violation:
[SNIP]
DEPARTMENT OF THE TREASURY
BUREAU OF ALCOHOL, TOBACCO AND FIREARMS
WASHINGTON, DC 20226
MAR 25 1999 903050:CHB
3311
Dear Mr. Bardwell:
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.
Sincerely yours,
Edward M. Owen, Jr.
Chief, Firearms Technology Branch
[SNIP]
AFAIK, the ATF issues an 'approval letter' giving manufacturers the nod to manufacture a particular break for post-ban rifles. When I emailed SOG asking them about an approval letter, they gave me this lame response:
We do not supply a letter from the ATF, but it is legal.
Thanks,
Tina
Sog Armory
...I seriously doubt they'd run to your side and pay for your lawyer if you got busted for using one of these, and I _have_ heard several stories about people having run-ins with the ATF about these things. There are plenty of such breaks that I've heard _are_ accompanied by a copy of an ATF approval letter. I would recommend finding one of these.