You didn't mention your bullet choice, as different brands have varying ogive's which will cause the problem with COAL and touching the lands.
Most short action magazines require a 2.800 COAL, or shorter, to function.
You will need to get the proper COAL information for the bullet that your using, or pick a dimension off the lands by .010" or .020", or whatever you wish to use.
I try to use .020" when possible, if the bullet length allows it.
Remember that rifle load COAL is not etched in stone.
NCsmitty