I drilled some lowers long time ago,they were 200,s I drilled a 1/2inch hole from the top side ,just all the way down,and drilled from down uder in the centre of the bullet to the new drilled hole and milled a scoop ,on the top I tapped thread ,and blocked it off,just 1 inch under the edge (on the top, I drilled another hole on 1 side ,and placed a 90 degree elbow with a hose and another 90 degree elbow ,just like you see on a nosecone application.
It worked great ,it was a little tricky because I didn,t know how much Ali there was in the cone section ,but there was enough in the old 200 casings ,there pretty massive in front to protect any collisions .