I was once OIC of the 106 range. Best show for visiting brass was to stack up about 30 wooden ammo boxes behind a gun and fire it... back blast turned them into toothpicks! Always impressive
But the weapon was impressive, too... I'll bet I could take a raw recruit and make him a tank killer in about an hour. The trigger was a push-pull knob... pull to fire the spotting rifle, when that was on, push to fire the main tube. Bang BANG.