Sighting in and load testing are different tasks with different requirements. When load testing, I want the most stability/repeatability as I can get. Front and rear rests, good comfortable position at the bench. Once I determine the best, most accurate and repeatable load, I then move to sighting in. Rough in the sights with a good rest, but then do your last adjustments from field positions (usually offhand for me.) Many rifles shoot to different points of aim when benched. Also, be wary of lead sleds with thin-wristed muzzle loaders. No recoil absorption can create cracked wrists.
ADK Bigfoot
ADK Bigfoot