My Gen-2 version .416 Rigby shot so well as it came out of the box, I never messed with it.
I just kept screws tight to no more than 65 inch-pounds,
being a weakling, that is about all I can do with a Fat Wrench screwdriver.
I only tested one powder charge with a half dozen bullets ranging from 380 grains to 410 grains,
all in one session, 3 shots with each bullet,
and settled on a load that afternoon, for my first safari in 2001.
All the bullets were accurate enough, roughly zeroed to check a 3-shot group at 115 yards.
Hey, the bulldozer driver was either drunk or confused on meters versus yards
when he made a first attempt at a 100-yard berm at the public range.
Choice load, same powder charge as John Buhmiller and Jack O'Connor liked for 400-grainers:
Here is the rifle that did it with a 1.5-5x20mm Leupold in Ruger rings:
One shot, broke his left shoulder and his heart and exited offside ribs,
he ran 50 yards and fell, gave the death bellow promptly in the mopane of Botswana's Okavango.
PH Ronnie McFarlane (supervising my Appy PH) gladly took my spare ammo off my hands when I left.
He had an original John Rigby & Co. .416 Rigby he was using for backup on elephant.
Hopefully it found good use for him.
While I was there, his client made a bespoke .500 NE H&H Royal fire both barrels at once, and the elephant still died.
Below will follow the images from the thread linked earlier, related to bedding, with my comments "Painted" onto some of them.
The RSM has a weird bedding system, but it is prone to excellent accuracy.