The HK51B is the fire-breathing, bastard child of an unholy marriage.  This monstrosity is accredited to the mad scientists at Vollmer and Co. who decided a belt fed .308 carbine had a place in the history books.  The 51B incorporates a feed mech robbed from the HK21 to deliver as many rounds to the battery as you can link up.

This gun is rowdy.

HK51B’s are shipped as pistols with or without a brace.  All NFA regulations apply.