Riverbend Gun Club in Dawsonville (close to where Forsyth County, Cherokee County, and Dawson County come together) is about a 15 minute drive from Cumming.
It's a private club, but the "matches" are all open to the public. They have service rifle matches, hunting rifle matches, highpower rifle shoots, etc. at the big rifle range that has one backstop and firing lines at 200, 300, and 600 yards.
I just took my M1 Garand to a hunting rifle sight-in day. Fired a dozen rounds at 200 yards, then a dozen more at 300 including several shot at a moving target, and finished off the last of my ammo at 600 yards (I was getting groups the size of a Maytag washing machine, but other shooters on the line with scoped rifles were getting groups the size of a Frisbee).
Check the calendar at the club's website to see what matches are coming up that would fit the kind of rifle you want to shoot.
P.S. It's a nice range to belong to as a member. I don't want to discourage you from becoming a member if you're so inclined.