This is his only surviving known photo, he does not look too happy:
J. W. Burleson, circa 1925
The foremost Civil War sniper rifle was the British “Whitworth”, a Civil War confederate "sniper rifle" that used a hexagonal barrel with hexagonal bullets:
If you can find a Whitworth rifle for sale, expect to pay over $70,000.
Check this out, a Civil War rifle being shot at 420 yards. Amazing!