I use a Rand Elite shield. This item is vastly superior to the more common Past pads.

I was turned on to it by an old BPCR shooter. He's a paraplegic and whacks the steel way out there with a 45-90 from a damned wheelchair. Got him a nice bull elk year before last on his own.... wheelchair and all. Somebody forgot to tell him he's handicapped!

They are available from Buffalo Arms at:

http://www.buffaloarms.com/

Here's a pic:

I use this when I compete in local informal practical rifle shoots. Everybody else uses 308s while I play with a 375. I shot 60 full power rounds once from the prone with this shield.

Really helps when working loads for the 500