You don't need a chronograph to get zeros at different ranges. Regardless of the group size you shoot, just get a zero at different ranges. Then write them on a label that ends up stuck on your scope.
If you use two different loads, you'll need two different labels; put on the one that matches your load. You'll also need different labels for the same load when used in different ambient temperatures and elevations. Keeping a log for different condtions and loads will help establish really accurate zeros for each.
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master