yeah, that's it. The housing was removed and trued up in a mill then two M4 holes put in the top to fit the pre-drilled weaver rail I had. Tehn you just need to trim some bolts down so they won't touch the barrel inside and away you go.

Just be careful with tightening them though as the metal is not the hardest out there.

Oh and if you have the right length of rail you won't need to take it off to still use the open sights. mine has a grove down the length that ensures it is hidden behind the rearsight when aiming.

I will have to dig out some pics at some point.