Mike; When I was in the Air Force and stationed near Rapid City I used to shoot lots of .223 ammo down range at PD's!
I used to go South and East of Rapid City on Hwy 44, from Caputa to Farmingdale and sometimes I'd go further toward Scenic!
Most of it is open to the public, but there is some that is private!
You will be able to find a place to shoot!
Have fun, wish I was going!