Here is how: Load five bullets to do the speed development. From the start load work up in one grain increments (half grain increments if bullet is less than 100gr) at the maximum col (cartridge overall length) the rifle will tolerate and chronograph the loads. Obviously the chrono needs to be reliable and read every shot. If the speed required is achieved, before five is done, that is a bonus and it often happens. Do not clean the rifle after the speed work up.
(* See Important remark below.)

Then load 15 rounds at the chosen powder charge and still at the maximum col for the rifle. Here is the most tedious part: Take your press and seater die with you to the range. Fire three for group. Run a dry nylon brush through the barrel and allow it to cool while the group is measured. Press the next three rounds 1.0mm (0.04") or (0.5mm [0.02"] if bullet is less than 100gr) deeper into the cases and shoot a group. Repeat the process and use your good judgement to determine what col your rifle wants with this bullet. You do this only once as HV bullets do not differ from batch to batch.
(This process does not work with jacketed lead bullets.)

The above is what Gerard Schultz, the manufacturer, says how you should do a load development.

* Important remark: "The faster you drive them, the better they perform."
However, don't exceed the manufacturer's maximum speed as indicated on Load Data sheet!