That's how all MK12 rifles look. The armorers at the Navy probably only had rifle length rails at their disposal when the MK12 was created, which is why you have an exposed gas block. It is a non-issue, IMO.
If you want, swap out the rail for something longer and it'll cover the gas block which should make you happy.
Edited by clandr1 (03/25/15 12:03 PM)