Hello CR, I bought a M-71 from BSA here at the fire with the bolt peep just like yours, KROIL is your friend, elevation was right on with mine too with 250 gr heavy jacket Barnes bullets at 2350 fps, and is easily adjustable by turning the big knurled wheel, which remains free wheeling save a little spring pressure to keep it secure.
The only adjustment I had to make was to move the sight left a lit, mostly due to the difference's in the way BSA and I held and fired the rifle.
KROIL, a toothbrush, and a bit if time will free up all screws for adjusting.