#html-body [data-pb-style=V6NKPWV]{justify-content:flex-start;display:flex;flex-direction:column;background-position:left top;background-size:cover;background-repeat:no-repeat;background-attachment:scroll}Introduced in 1966 as the first "mil-spec" adjustable stock. Previous versions were complicated prototypes that required extensive manufacturing processes. This design was eventually phased out and replaced with a polymer version that looked similar to this model. The polymer was then phased out and replaced by the M4 stock that is still in current use.