I have a modern replica rifled musket that fires .50 cal pure lead round bullets. I haven't actually weighed each individual bullet, but they are absolute huge and fucking heavy as shit, even compared to incredibly more powerful modern rounds like a .338 Lapua. It's probably heavier even than a modern .50 BMG bullet (although I've never personally seen how heavy just the projectile is for those).

Even with modern metal, modern computer-drilled rifling, modern black powder (far more consistent and pure, also stored in truly airtight plastic containers - impossible for armies in the past), and with CNC machined round shot, it is maaaybe accurate to about 75-100 yards. If you're lucky (although I will admit I am not the worlds best shot, and also it kicks like a mother... even with 100 grains of black powder and a HEAVY AS FUCK gun, it kicks much worse than a .300 Win Mag). And even at that range you have a SIGNIFICANT bullet drop due low velocity and lack of aerodynamics. You can get copper plated vaguely bullet-shaped ones that have a passing similarity to a Minie ball (although you just have to ram it home by brute force - they don't deform when you fire it like the OG ones do) and those might get you out a bit closer to 150 yards.

And again this is a .50 cal bullet - close to 50-75% smaller in volume and weight than the ones they used in the Civil War. But yeah, regardless of the "low" velocity, you should see what it does to a tree when you hit it - holy shit dude.