Originally Posted by ErinMT
My hands/front of grip and trigger guard supported from underneath. making sure not to put pressure on the dust cover and slide and none on the magazine or bracing the bottom of the grip.
And all the shooters are experienced Glock shooters.
Try supporting only your forearms/wrists -- don't let any portion of the gun touch the rest. A pistol, especially a light polymer pistol, can bounce away from anything it touches, just from the concussion.