{HEAD ~ An apparatus} for measuring a projectiles transverse displacement at muzzle exit of {TAIL ~ a gun tube} which comprises: 
{ HEAD ~ An apparatus } for measuring a projectiles transverse displacement at muzzle exit of { TAIL ~ a gun tube } which comprises :
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH