In preparation for delivery of my new Heym, I want to develop some handloads that will simulate their factory loads. I have RL-15, IMR-4831, H4831, Hornady brass, F215s, Hornady softs and solids, and Woodie softs. Where should I start my loading - i.e what starting level for each powder? Anyone know what powder they're using?

This is my first double. How many test rounds at each level should I load? I normally load 6 at each level for my bolts.