This issue of Soldier of Fortune magazine has very good article on the ARMS S.I.R. (March)
and this months (May issue/subscribers) has article on page 52 by Odin Crowe, "Warriors of the Urban Spawl", (CQB & MOUT Explained) in which operators (in pics) are all using S.I.R. equipped uppers.
Incase anyone might be interested.
FWIW if your not reading SOF your missing some great coverage of the Afgani war.