Modern rifle rounds like the tiny 55 grain 5.56mm, do drastically more damage than the low velocity Civil War rifled muskets.

Why?

Hydrostatic Shock. Ask any trauma surgeon about modern high velocity ammunition and the wound cavities they create.

It is why that Antifa had his bicep explode trying to take down Kyle.

The couple of pounds of meat the evaporated in a pink mist, is the same few pounds of flesh that evaporate into mush inside your torso, hidden under the skin and fat that now has become a carrying pouch for what is left of your internal organs.

Going back to the Civil War, the main reason amputations occurred was to prevent death due to infection and then even if the wound was not infected and conservative treatment was given the patient would die due to complications associated with fractured bones.

By World War I we had invented traction therapies that allowed boney involvement injuries to become mostly survivable.

Why did the surgeon pin all the fragments back into place? To keep you from spending a month in traction, so that a fatty embolism from the bone marrow tissue doesn't kill you, while the pieces shifted around during the healing process.

A lot of the processes were not known in those Civil War years, but they DID know that amputation into uninvolved tissue, has the highest survival rate by far.

Minnie Ball or M-16/AK-47 round to the body? I'd have to choose Minnie Ball and a trauma team on standby. The other two will be a morgue visit.