7 ▁mm ▁automatic ▁air ▁defense ▁gun ▁M 1 9 3 9 ▁( 6 1 - K ). ▁In ▁the ▁late ▁ 1 9 5 0 s , ▁the ▁People ' s ▁Liber ation ▁Army ▁Navy ▁updated ▁the ▁Soviet ▁V - 1 1 ▁naval ▁gun ▁by ▁incorpor ating ▁a ▁semi - autom atic ▁operation ▁to ▁reduce ▁man power ▁needed ▁to ▁operate ▁the ▁gun . ▁The ▁result ▁was ▁the ▁Type ▁ 6 1 , ▁named ▁after ▁the ▁year ▁in ▁which ▁the ▁development ▁was ▁competed . ▁Type ▁ 6 1 ▁incorpor ated ▁the ▁semi - autom atic ▁oper ational ▁mode , ▁but ▁as ▁a ▁pre ca ution ary ▁measure , ▁the ▁manual ▁oper ational ▁mode ▁of ▁the ▁original ▁Soviet ▁V - 1 1 ▁gun ▁is ▁also ▁retained ▁as ▁a ▁backup . ▁ ▁Other ▁then ▁satisf actory ▁results , ▁the ▁Type ▁ 6 1 ▁did ▁not ▁enter ▁mass ▁production ▁because ▁China ▁was ▁still ▁recover ing ▁from ▁the ▁political ▁tur mo il ▁caused ▁by ▁the ▁Great ▁Le ap ▁For ward , ▁during ▁which ▁time ▁many ▁military ▁programs ▁were ▁scale d ▁back ▁or ▁can ce led ▁altogether . ▁As ▁a ▁result , ▁the ▁Type ▁ 6 1 ▁only ▁entered ▁Chinese ▁service ▁in ▁very ▁limited ▁numbers ▁and ▁never ▁saw ▁action ▁in ▁any ▁batt les . ▁ ▁Although ▁limited , ▁the ▁service ▁experience ▁of ▁the ▁Type ▁ 6 1 ▁proved ▁that ▁the ▁semi - autom atic ▁oper ational ▁mode ▁design ▁was ▁reliable ▁and ▁the ▁manual ▁oper ational ▁mode ▁was ▁not ▁needed . ▁In ▁ 1 9 6 5 , ▁the ▁Type