David is right, of course Nevill couldn't 'wrestle' with anyone with such a dreadful injury to his arm. It is a farce that it was ever claimed he could have. He had shocking injuries by that time.
Of course Nevill & Bamber wrestled for the rifle.
The judge said the aga scratch marks on the silencer shows it was on during the massacre. Why would Bamber scratch the aga & smash a ceiling light if he always had total control of the rifle ?
Nevill was fighting for his life & would use one arm & his body weight or both arms to try to gain control of the rifle. Regardless of the pain which I doubt he would notice in the heat of the moment.