Saw a guy do it years ago at the range.
He wasn't paying a lot of attention to what he was doing. Recoil was apparently pretty bad.
He was also loading from an open can of black powder sitting on the bench next to his flintlock.
I mentioned that as being bad practice, he didn't seem to care, so I moved about a dozen benches farther down the line.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.