▁dow nt urn , ▁Bow ser ▁went ▁ahead ▁with ▁design ▁and ▁production ▁of ▁his ▁most ▁am bit ious ▁project ▁to ▁date . ▁Working ▁from ▁actual ▁Union ▁Pacific ▁Rail road ▁blue print s ▁with ▁the ▁aid ▁of ▁an ▁early ▁mechanical ▁calcul ator , ▁Bow ser ▁re created ▁the ▁ 4 - 6 - 6 - 4 ▁Ch allen ger ▁in ▁HO ▁scale . ▁The ▁end ▁result ▁was ▁an ▁accurate ▁model ▁that ▁set ▁Bow ser ▁apart ▁from ▁other ▁manufact ur ers ▁of ▁the ▁day . ▁Unfortunately , ▁the ▁manufact uring ▁issues ▁encountered ▁over ▁the ▁last ▁few ▁years ▁had ▁de ple ted ▁the ▁company ' s ▁fin ances ▁and ▁Bow ser ▁was ▁forced ▁to ▁accept ▁additional ▁contract ▁work ▁to ▁pay ▁for ▁production ▁of ▁the ▁Ch allen ger . ▁ ▁After ▁the ▁contract ▁ended ▁and ▁the ▁Ch allen ger ▁was ▁in ▁production , ▁A ches on ▁chose ▁to ▁force ▁out ▁Bill ▁Bow ser ' s ▁portion ▁of ▁the ▁partners hip . ▁Bow ser ' s ▁personal ▁fin ances ▁were ▁nearly ▁de ple ted , ▁and ▁he ▁was ▁unable ▁to ▁match ▁A ches on ' s ▁buy out ▁offer , ▁forcing ▁him ▁to ▁leave ▁the ▁company ▁in ▁ 1 9 5 5 . ▁ ▁Since ▁the ▁factory ▁was ▁in ▁full ▁production ▁at ▁the ▁time ▁of ▁Bill ▁Bow ser ' s ▁ou ster , ▁A ches on ▁was ▁able ▁to ▁stock p ile ▁a ▁considerable ▁number ▁of ▁k its ▁to ▁sell ▁over ▁the ▁next ▁few ▁years . ▁ ▁Bill ▁Bow ser ▁established ▁Bow ser ▁P rec ision ▁Product s