Nick,
Hook yourself up with one of these (see below links)or any of a variety of sliders, and those 100yd shots will come much easier, as will the 70's. I have the Cobra Sidewinder XL, and it's capable, however, my eyes aren't capable any longer of anything past about 70yds. Figuring where to put a 40yd pin on a 70 yd shot has a lot of "Trial and Error" to it, pick up a slider, and all of the sudden, things totally change.

http://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_95767_400014011_400000000_400014000_400-14-11

or

I have the Cobra which is almost exactly the same as this....(.019) pins help a lot!!!

http://www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_79520_400014011_400000000_400014000_400-14-11