nope thats a compensator
it hides no flash
ARs cannot remove the pistol grip evil feature with a thumbhole stock
http://www.jpar15.com/customer.htm
After September 14, 1994, no lower receiver can be completed to form a
"semi-automatic" rifle that has an ability to accept a detachable
magazine and has two or more of the following features:
A.a pistol grip that protrudes conspicuously beneath
the action of the weapon
B.a flash suppressor or threaded barrel designed to
accommodate a flash suppressor (a recoil reducing
device is considered acceptable)
C.a folding or telescoping stock
D.a bayonet mount
E.a grenade launcher
What this means is that you may have a post ban ("post ban" meaning
assembled after 9/14/94) AR-15 rifle which has only one of the listed
features, and that is the pistol grip. It was previously believed by most
people in the industry that "thumb-hole" configuration stocks were a way
to technically eliminate the "pistol grip" feature on a rifle.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>However, BATF
has now interpreted the Crime Bill in such a way that it isn't possible to
construct an AR-15 type rifle without a pistol grip regardless of the stock
configuration. Because there is no way to eliminate the pistol grip feature,
you may not have a flash suppressor or a muzzle that is "threaded to
accept a currently manufactured flash suppressor." [/quote]A compensator or
recoil reducing device is acceptable as long as it is attached permanently
by pinning, welding or high temperature silver solder or attached with a
thread pattern for which there is no flash suppressor made.