Killing is a function primarily of accurate placement of a projectile, whatever you use. If you hit a vital organ or two, the animal is going to die. When it dies and where it dies is a function of both shot placement, and the weight of the ball.
Heavy balls penetrate further than do lighter balls.
Because all round balls have lousy ballistics Coefficients, pushing a ball out the barrel at higher velocity is Not necessarily going to translate into that same velocity increase at the target. In fact, drag factors increase with the speed a round ball enters the air, slowing the RB faster if it goes faster. So, the longer the distance to the target, the less delivered velocity arrives at the target, regardless of how much faster the ball leaves the muzzle. Worse, the faster the ball is sent down range, the more likely that it is not going to shoot as small a group, so that accuracy suffers when you increase the velocity of a round ball above an optimum speed. That is a function of the air turbulance created by the drag factor on the ball, as well as the reduction in velocity the further the ball travels.
ABout a year ago, someone posted some ballistics for a .50 caliber Round ball leaving the muzzle at a sizzling 1900 fps. At 50 yds, the velocity is down to 1409 fps. At 100 yds, the velocity is down to 1041 fps. at 120 yards, the velocity is down to 959 fps.
He zeroed his gun at 110 yards. At 50 yards, the ball was hitting 2.45 inches high. At 120 yards it was 1.46 inches low. That is pretty flat shooting, as it goes. However, as you increase that distance the ball drops faster and faster, making accurate range estimation critical to accurate placement of a RB on any animal.
If you look at those velocities you see that even at that fast MV, he is losing 25% of his velocity withing the first 50 yards, and more than 45% of his velocity out at 100 yds.
If you would make any conclusion about a black powder rifle shooting round balls, its that this is basically a 150 yard and less firearm, and anything beyond 100 yards requires a lot of practice for the shooter to hit any sized target, considering all the factors affecting that ball.
That is why the invention of tools precise enough to make conical bullets of a proper size, and barrels of an equally predictable size or diameter, changed the course of history of the development of firearms. It was well after our American Civil War, that manufacturers began to control bore dimensions to the thousandth of an inch, however, and true accuracy was being seen in production rifles. Custom rifles were ahead of production equipment by at least 25 years. If you are really looking for a gun that will kill accurately out past 150 yards, then I suggest you consider a gun designed to shoot conicals. There are, for instances, T/C rifles chambered for .58, with fast twists, that can shoot conicals at longer ranges and insure accurate hits, and quick death at those longer range. You may need to do some modification of the stock design to control recoil,But a .58 will do what you seem to be wanting.
Cheers. :thumbsup: