Hey Mike,
My (more limited) experience mirrors Daryl's.
I discovered that in Blackpowder Cartridge Rifle (BPCR) or muzzleloading, the bullet/ball is so slow it takes a long time to get out of the muzzle. Also, the barrels are much longer. Makes it worse. You know all of this sir.
High-power modern rifle benching techniques didn't work for me.
What I figured out was that the barrel ends up whipping and bouncing off the front bag long before the bullet/ball is out of the muzzle. That made for bad shot dispersion.
I also want my rifle to shoot to the same POI off the bag or offhand (or at least close).
As Daryl said, I hold the forestock where I'd hold offhand, and then put the back of that forward hand on the front bag. I grip it tightly to control the barrel.
In the rear I use a big soft beanbag. I burrow the butt down on top, and push my chest into it from the rear. That way it is acting more like offhand, but I am pretty rock steady.
It seems to work for me. Works for hard recoiling modern rifles too.
The folks in BPCR that use cross stick under the barrel have all sorts of methods for determining the node along the barrel where there is least movement, and place a piece of tape there to use the same spot each time. Where's Dan? I am sure he can fill everyone in. Some use baby powder on top of the barrel and tap it to identify harmonics and nodes.
I would NEVER use a lead sled with a rifle, especially not with a valuable longrifle. As was said above, the only thing to give is the stock! If you are shooting a rifle that kicks so much you can't shoot it well, you need to drop down in caliber or up in weight. As my friend Dave said, "There's no future in being kicked!" He wins medals at Friendship, so he's no beginner or wimp.
I hope this helps Mike. I think you are asking about hunting rifles, not target rifles, so that is what I was talking about above.
Best wishes, Marc
