a locking assembly to frictionally lock {TAIL ~ the breastplate} to {HEAD ~ the shaft} at at least one arced groove 
a locking assembly to frictionally lock { TAIL ~ the breastplate } to { HEAD ~ the shaft } at at least one arced groove
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH