Skullmount is exactly right - it depends on the bullet weight and amount of powder. You should have an owners manual for your Black Diamond which will have a ballistics table in it, which will give bullet drop data for certain bullet weights and powder charges.
The table for a T/C Encore shows that: with a powder charge of 100 grains of Pyrodex, and a 240 grain Hornady XTP sabot, a bullet sighted dead on at 100 yards will drop 4.8 inches at 150 yards, and will drop 14.1 inches at 200 yards. So you should be able to look the data up for your rifle.
Note that the bullet TYPE comes into play also, as a hollow-point bullet will have a different ballistics coefficient than a boattail type bullet like Deadcenters, and both will naturally be different than a roundball.
A ballistics calculator can give you theoretical bullet drop and other data at various ranges under different conditions; you can find these online, or buy one.
The figures in the tables are just approximations, as your rifle will shoot differently than the one used to generate the tables. You have to shoot yours at the range, sighted 2 inches high at 100 yards, then shoot it at 150, 175 or 200 to find the actual drop. Which is great, because now you get a lot more time shooting. :lol: