You're right BAR, it was meant to bear the weight of your shoulder or chest. The same tool had loads of uses on the Bren and BESA too.. Buffer nut, pistol grip, No1 and 2 pistol chamber scrubber etc etc. I've still got one. Our brace was a one-size-fits-all, unlike the commercial version with an adjustable 4-jaw drill chuck for square shanked wood drills