Graybeard, as you probably know, the bench is the worst place to shoot heavy kickers, but that is where we all go to develop loads. Real benchrest guns are heavy as heck, and in small calibers, so we lean into them and hold them lightly for best accuracy. Great way to get a scope in the eye, or bruise a shoulder with a magnum, or even a standard caliber in a light gun. But if you can get in a more upright position so you can roll with the punch you won't feel a thing. The Brits fire their Nitro Express guns and 4 bores standing, with elbows on a high table. Sandbags on the hood of a pickup work well. If I can't find a short enough seat, I kneel behind a picnic table. I can still get rock-solid holding on to the forend and resting my hand on the bag.
Also, adding a pound of weight to the gun is easy, and will work wonders.