The Daniel Defense S2W bbl is (was???---not sure if they still produce/offer it) their heavy barrel option several years ago. They wouldn't tell you that this made it MD legal over the phone-- but it was part of their marketing description on their website. Can't speak to the "government profile" but unless DD describes it as heavy barrel in writing somewhere I'd be hesitant.Daniel Defense sells a barrel, on its built long guns anyway, which is their HBAR. It has a 'Government Profile' which means it is not a light pencil barrel. Looked at the carbine in person...you could see the contour through the handguard. That is the heavy barrel the military used on the A1 upgrade to the M4. If I am incorrect...let me know.