My friend Ben Phillipi just put this together on his favorite gun, the HK51 ‘Angry Gun’.
You do know the HK51 yes? If not, here is a brief primer:
These were never made by HK and basically take a G3 or its semi-automatic clones (PT91/HK41/HK91/SAR 48 et. al), chop em down to a 8-inch ish barrel (!) and deck them out with MP-5 furniture. The result is a 24-31 inch gun that is typically an SBR by definition and, since you have to get the tax stamp anyway, usually select fire. HK followed up with this gun with their HK53 later, which is the same concept.
And they are a blast to shoot. I mean, who doesn’t want to kick a 3-pound 7.62x51mm NATO out on full-auto?
