Trust me, this is the answer in general. Whiskering is done to 400 paper, not more or less. The first can be 320 then 400. But only 400 after that. Anything heavier than that cuts too much wood and does nothing. 3 times. Wet stock, let dry or better, heat with a torch or other heat source. Then 400 paper. Obviously your stock has to be finished to 400 in the first place. Keep the paper fresh. You're cuting off the raised grain, not depressing it. This is the method Bivins used to get those great finishes.
Burnishing is a whole different cat. No one had 400 paper back then. Likely Am. rifles were finished this way in general.
BUT. They did have methods to create a similar finish to the 400 paper Bivins thing.
I think, abrasives and oil worked into thin and tightly stretched felt are very effective.
I've had English work of the late 1700's where scraping and burnishing could not possibly have produced the finish. It's simply glass smooth perfect.