CS forces used rifle balls (minies) with no grooves (or rings), two grooves and three groves. Union Forces used much of the same type of ammunition. The grooves were for lubrication purposes. The two groove vs. three grooves generality was the result of CS usage of a distinctive two groove, crimped paper cartridge called a Gardner while the Union did not use these. There were many varieties of rifle ammunition used both imported and domestic and there are a lot of subtle differences. There are books available to identify CW ammunition and it is the only way to positively ID a particular bullet if you are not familiar with them.