Under this effort a 20mm Semi-Armor Piercing High Explosive SAPHE ammunition, designated the PGU-2B, was designed, developed, fabricated, and evaluated. This design incorporated an all-impact angle base fuze evolved from the feasibility effort. The resulting 20mm SAPHE round is designed to meet or exceed the technical requirements of the M50 series ammunition. It is also designed to be directly interchangeable in the present M39 and M61 gun systems without change or modification to the gun or feed with the exception of coil spring rates. The initial baseline development included contractor design, development tests, and delivery of over 3,000 cartridges for Government evaluations. Additional effort included fuze design modifications to investigate the feasibility of increasing the minimum arming distance to 6 meters, with 15 meters desired, development tests, and delivery of six cutaway display models.