Has anybody ever tried to convert an existing AR barrel with carbine length gas system to a mid, or even rifle length? Drilling the new gas port is straight forward enough, i assume, but sealing the existing carbine length port is the tricky part. I've considered a low profile gas block installed upside down but suspect there may still be some gas leakage. Would a quick mig weld warp or disrupt the barrel is some other way? Possible drill and tap the carbine length port to the smallest screw size available?