I must agree with cheesy-Q the head needs some work and mabey the arms wouldn't be so lanky if they 4 studs long in gun mode insted of 6. all in all I must say 4/5 for good I like it but there are areas that need work.
Great job, though I think the scope is too far back and the barrel is too short. Maybe you could you techic gears and axles? Anyways, I love how you made it transform and concealed it perfectly, which totally outweighs my cons. 5/5!