. ▁The ▁" G un Val ▁Project ", ▁seven ▁F - 8 6 s ▁and ▁five ▁veter an ▁pil ots , ▁was ▁attached ▁to ▁the ▁squad ron ▁to ▁test ▁arm ament ▁modifications ▁in ▁combat . ▁North ▁American ▁A viation ▁removed ▁the ▁six ▁M 3 ▁. 5 0 - cal iber ▁machine ▁guns ▁from ▁four ▁late - production ▁F - 8 6 Es ▁and ▁six ▁block - one ▁F - 8 6 F s , ▁expanded ▁the ▁size ▁of ▁the ▁gun ▁b ays , ▁strength ened ▁the ▁surrounding ▁frame ▁assemb lies , ▁and ▁mounted ▁four ▁newly ▁developed ▁T - 1 6 0 ▁ 2 0 mm ▁can non ▁in ▁their ▁place . ▁Having ▁a ▁similar ▁rate ▁of ▁fire , ▁the ▁can n ons ▁were ▁expected ▁to ▁significantly ▁increase ▁the ▁Sab re ' s ▁le th ality ▁over ▁that ▁of ▁the ▁machine ▁guns , ▁whose ▁arm or - p ier cing ▁inc endi ary ▁am mun ition ▁was ▁usually ▁in effect ive ▁against ▁jet ▁aircraft ▁above ▁ 3 5 , 0 0 0 ▁feet ▁of ▁alt itude . ▁However , ▁the ▁heav ier ▁weight ▁and ▁bulk ▁of ▁the ▁can n ons ▁and ▁am mun ition , ▁while ▁providing ▁greater ▁effective ▁range , ▁fl atter ▁traject ory , ▁and ▁higher ▁velocity , ▁limited ▁the ▁F - 8 6 ▁to ▁only ▁ 4 0 0 ▁total ▁r ounds , ▁which ▁reduced ▁its ▁total ▁firing ▁time ▁by ▁nearly ▁ 7 5 %, ▁from ▁ 1 6 ▁to ▁ 4 . 6 ▁seconds . ▁ ▁G arrison ▁worked ▁closely