Bob,
I have a 338 Mag Vanguard S2 and use a slip-on Limbsaver sorbothane pad when I shoot it off of the bench. Takes a whole lot of the sting out of it.
Thanks Partisan. The pad on it is quite good really. With a little listening to others and self coaching however, it turns out it was my technique. I was holding the rifle in soooo tight that I was causing the scope to occasionally whack me. I just needed to relax a bit. I also started using decent bags and got myself a lot more comfy at the bench.