Hi Geoff,
I know this will go against the norm for bench rest but have you tried front bag only with your right hand rested on it and the foretock rested on your hand? It may help? I find my recoiling springers better this way.
Another thing you could try is putting material of different slippiness over the front rest in case the rifle is more accurate when allowed to slide on the front rest or when held more firmly in place by friction.
Cheers
Rich