The B.C. of a .490 roundball is .056. The muzzle velocity with 90 grains of 2f powder is 1950 with a muzzle energy of 1478. In order for the rifle to hit 4" high at 50 yards (V=1369 & E = 736), you would have to sight dead on at 138 yards. At 25 yards you should be 1.7 inches high. At 75 yards = 5.2 inches & E= 531. At 100 yards = 4.7 inches & E=416. At 125 yards = 2.2 inches & E= 349. Dead on at 138 yards . At 150 yards = -2.7 inches & E= 302.

I want to say that numbers mean very little when you talk about roundball. Velocity is good in most cases, but the rifle's muzzle energy is very poor. The roundball is good as far as expansion and take down ability. The only thing I would question with your set up is why you sighted so high at 50 yards. Sighting in only 1.6 inches high at 50 yards brings all your numbers much closer together for the kind of distance you should attempt with a roundball. This puts you dead on at 100 yards. I personally sight my roundball rifles in at 75 yards. This brings all my ups and downs much closer out to 100 yards. But then I do not like to shoot further then 100 yards with a roundball. And probably would not unless there was a perfect (and I do mean perfect) shot.