I have a Henderson 3" arca rail mounted on my stock just in front of the action screw. So it locks in tight.....and the crosshairs don't move at all, until I shoulder the rifle. Unless I have something to rest my right arm/elbow on, it's not steady. If I'm sitting in a chair I can rest my elbow on my knee and it's fine. On a bench I can use a bag or rest the elbow on the bench. It's when I have nothing but me, the tripod and the rifle that things get iffy. Make no mistake, I'm working on it....but until I find that magic position, I'll make sure I have a place to sit.
Yeah. Having a place to support that
Rear elbow helps a lot .
The Henderson ultra lite Arca is a nice setup. Wish he still made them. The pic of my buddies 7mag up top had that Henderson rail as well.