I did a search using google and came up with the same web site. I loaded the formula into an EXCEL spreadsheet and came up with some pretty low BC's.
To bad ExBal will not except a BC below 0.1. Found that out after I posted this question.
The muzzleloader group at my gun club is complaining about having to shoot down a slight grade for our 50m berm as compared to the 100m berm. They want to shoot on perfectly level ground.
I'm thinking that a 10 to 15 degree slope is not that big of a deal, looks like it might amount to a little over an inch - if that. Given that they are using iron sites, I just do not see it having that dramantic of an influence on the ballistic curve. I think it is more of a head game than anything else.
Thanks for the bandwidth... Don