{TAIL ~ Each} of {HEAD ~ said walls} defining a secondary receiver chamber sized to receive a magazine cartridge of rounds a shorter length than otherwise provided for in a rifle 
{ TAIL ~ Each } of { HEAD ~ said walls } defining a secondary receiver chamber sized to receive a magazine cartridge of rounds a shorter length than otherwise provided for in a rifle
TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH