Type 1 DAVY CROCKETT HIGH-LOW PRESSURE spotter 20mm next to adopted tactical version of the case. Type 1 is on the right . It is a heavy walled blued steel case with rim. The spotters are reloadable. In this type the 4 notches in the rim are to effect the removal of the head. The 2 deep spanner holes in the tactical version are for the same. LAKE CITY ARSENAL experimental.
Only 3 examples of this known. 2 are in Woodin Lab.