Fellas, here is Xausa's Sled. He reports:

"Yes, it gives against the recoil. A welder friend of mine simply notched a piece of 3" channel iron and bent it 90 degrees at the weld, then welded the notch back together. I bolted the resulting fixture to a piece of 3/4" plywood, upon which I rested my bench rest stand and as much weight in the form of lead shot as I found necessary. The whole contraption was placed on the bench rest table top and allowed to move in any direction, with only the friction between the plywood and the table top restraining it.

In use, I simply placed the butt of the gun against the upright portion of the fixture, rested the foreend in my hand and my hand on the sandbag on the benchrest stand, held the butt firmly against the fixture and the fixture against my shoulder and fired. Depending upon how much shot I was using, the whole thing moved either rapidly or slowly and majestically to the rear. This added about 1/4" to the length of pull of the rifle, which to me was much more satisfactory than placing a lead shot filled "sissy bag" between the rifle butt and my shoulder, another alternative.

I got the idea from the "Preuss device" (Preussgeraet) which I had seen used in Germany to sight in rifles, including drillings and double rifles at the factory and at gunmaker's establishments.

When I started development of the .505, based on John Buhmiller's experiences, I set up the device and started with a moderate load and increased the powder charge in one grain increments until I reached the desired velocity. I think this would have been torture without the device and no problem at all with it, given that the rifle only weighs 8 3/4 pounds.

After I had settled on a load, I hardly used it at all, since my practice was with lower powered lead bullet loads and the jacketed bullets were too rare and expensive to waste on targets and tree stumps."

And his custom wildcat .505 it was built for:

And best of all, results {!!!}!