lik on ▁purchased ▁His p ano - Su iza , ▁they ▁under to ok ▁a ▁ren aming ▁exercise ▁for ▁all ▁of ▁their ▁weapons . ▁The ▁H S . 8 2 0 ▁was ▁then ▁known ▁as ▁the ▁K AD , ▁meaning ▁K annon , ▁A ▁for ▁ 2 0   mm ▁and ▁D ▁as ▁the ▁fourth ▁model . ▁O er lik on ' s ▁own ▁ 2 0 × 1 2 8   mm ▁became ▁the ▁K AA ▁in ▁the ▁elect r ically - f ired ▁version , ▁and ▁the ▁K AB ▁in ▁the ▁gas - oper ated ▁version . ▁ ▁The ▁United ▁States ▁produced ▁a ▁slightly ▁modified ▁version ▁of ▁the ▁H S . 8 2 0 ▁as ▁the ▁M 1 3 9 . ▁It ▁saw ▁use ▁on ▁a ▁number ▁of ▁vehicles , ▁including ▁the ▁US ▁Army ' s ▁M 1 1 4 ▁and ▁the ▁Marine ▁Corps ▁Am ph ib ious ▁Ass ault ▁Ve h icle ▁and ▁the ▁ill - f ated ▁M IC V - 6 5 ▁series ▁of ▁arm ored ▁vehicles , ▁including ▁on ▁a ▁pal let ised ▁mount ▁in ▁the ▁cabin ▁of ▁a ▁Bell ▁U H - 1 ▁hel ic opter . ▁ ▁The ▁ 2 0 × 1 3 9   mm ▁round ▁was ▁also ▁widely ▁used ▁in ▁a ▁variety ▁of ▁other ▁weapons , ▁including ▁the ▁Rhein met all ▁M K ▁ 2 0 ▁Rh ▁ 2 0 2 ▁( M aus er ▁M k . 2 0 ) ▁and ▁ 2 0 ▁mm ▁mod èle ▁F 2 ▁gun .