US Bolt assembly for the M24  20mm auto cannon. Cannons were used as aircraft cannons during ww2 and the Korean war. Used on these aircraft platforms. 

Convair B-36 Peacemaker

Boeing B-47 Stratojet

Douglas B-66 Destoryer

F-86K/F-86L Saber Dog

F-89C Scorpion

And used as an experiment ACH-47A Chinook. 

This piece is just the assembly and does not have the internal parts or firing pins. Its in good condition with very slight rust spots from storage (We just applied protection lube to help stop further storage rust) 

This makes a good collection piece or paperweight.