Disco died in 1979...
I still own the pistol grip that came on my M-500D...
The real convincer was the hand to hand (with weapons) matches me and my buddies engaged in...
The person with a PGO gun had less retention ability while also facing physical attack upon their person... We didn't have simulated role playing... we literally went after one another like we meant it! Full contact with requisite injuries... The hand gun holder and full stocked long gun handler were both well better at retention and defense...
Brent