I dont use chairgun anymore. I use strelok pro and it covers almost every scope you can find. Strelok pro also has the drag function for pellets so you only need to enter in the BC data for the pellet you are using. With chairgun not updating its data base for pellets you have to do that anyway for most of the newer offerings. It also asks for the length of the projectile but thats easy to measure if you have calipers but I dont know how much that effects the data so it may not be a big deal if its not exact.