The 1,000 pound armor piercing bomb is a converted 12 inch mortar shell. The modifications included the removal of the base fuze and the incorporation of a tail-base plug which adapted the shell to receive a tail adapter booster, the M110, and a box type fin assembly by means of a coupling extension and fin lock nut. The fin lock nut holds the fin assembly around the bomb body in the same manner as described for the GP bombs, except that the threads to seat the fin lock nut are provided by the coupling extension.
Attached to the bomb body are two suspension bands which provide the lugs for double suspension. These bands fit around the circumference of the shell and are bolted in place. For dive bombing purposes, the Trunnion Band M3 Al was included in the complete round. The final addition was a type A arming wire assembly .064 inch in diameter for use in the tail fuze. This bomb can be identified by the blunt mild steel pellet on the nose.
Total length of this bomb is 70.88 inches and the diameter is 12 inches. The case is 2.3 inches thick and weighs 983 pounds.
The 1,000 pound AP Bomb M52A1 differs from the M52 only in that it has a new adapter booster which has a greater tetryl booster charge. US Bomb, 1000 lb AP, M52, M52A1 (bulletpicker.com)