Ya I downsized mine to accommodate my shooting, I was running a 500cc and had a Maddog Raptor stock and it was exactly inline with the Butt stock pad on the stock shelf.....so on a few shots changing my posture, I was inadvertently putting a firm hold and hitting the tank with my shoulder causing my top hat o rings to sheer off moving the bottle and valve...
I took it down to 480cc which def does the trick and now have a more comfortable posture shooting the Tex....I tether as well so smaller sized bottles really don't even matter when tethered bench shooting comes into play... and in the field as well as your very much aware that you really only need one shot to take down game.