20 mm Multipurpose M70 was developed and qualified for the RNAF F-5 Aircraft in 1970. Thereafter, Nammo developed a range of ammunition for Air Force, Navy and Army applications ranging from 12,7 mm up to 40 mm. The last caliber to enter the Multipurpose family was 30 mm x 173 MPT/SD.
The pyrotechnic ignition train results in a deflagration (not detonation) of the round creating larger fragments than a detonation.
- Low burning propagation velocity of both the pyrotechnic charges and the explosive gives the delayed action of the MP round
- Slow pressure build up gives the characteristic MP fragmentation pattern which is a 20-30 degree cone along the line of fire.