Just a new disign (colt 45 grip),Fred actuly originated from the auto industry ( pattern maker).So he kinda believed a new model every year was best.As for the breakage of the 1963 the only one that broke was the type one dog leg magnum,and later discoverd,not do to disign flews.But do to step thru stringing methiod.Bear did recall many 1963 dog leg mags.I have a 1963 Kodiak 55# I have shot at least 5,000 plus time with no problems.Hope this helps.....bowodoc