Shavers sight instructions

[jgh4445]

My Lyman Model of 1878 ( actually a close copy of the 1877 Sharps by Pedersoli) is wearing a Lee Shavers long range sight. Lyman 17 front globe. I have the .22LR insert for the barrel and was shooting decent groups with it at 100 yds this past weekend. In order to hit center of the 6 inch bullseye, I had to use the tallest post I had with the rear sight adjusted all the way to the bottom and actually bottomed out.

Now our range has opened the 300 yd range back and I want to try my 45-70 loads at 100, 150 and 200 yds. I'm pretty sure I can get back on at 100 easily enough, but having lost the instructions for this sight, I'm wondering what the formula is for dialing in the drop at 150 and 200.

I'm shooting a postell 535 gr over 64 gr 1.5 swiss with .200 compression and two .030 wads. Don once gave me a hint on how many hash marks on the staff it would take to get to 200, but I lost that too. Anyone with experience with this sight want to hazzard a guess ? OH, its gonna be even more fun cause the 150 and 200 yd shots will have to be made from X sticks. We have no bench set up. Doubly fun since I've never tried shooting from them before. Heck of a first post huh?