I am currently reading The Rifled Musket in Civil War Combat: Reality and Myth by Earl Hess. This is a very good book that really fills out the argument made by Paddy Griffith years ago, that the Rifled Musket did not change the battlefield. However, I am impressed by the healthy dose of statistics from Chickamauga. Here are some examples:
28th Alabama Infantry held up for 10 minutes in a firefight at 20 yards.
74th Indiana Infantry held its fire until there Confederates were only 60-70 yards away.
Wilder's Brigade, as were their usual tactic, let the Confederates get to within only 50 yards before opening fire.
Now the forested enviroment made an impact on these ranges to some degree, most soldier accounts claim initial visibilty was between 100 to 150 yards through the forest. This is still almost point blank range, literally waiting until you can see the whites of their eyes. So it really ties into why soldiers are fighting on their backs in this fight.