Free: Contests & Raffles.
Start light and work your way up. I think it has to do with alot of what is in books and then lots of time on the range. Checking pressure on your brass, seeing how they shoot etc. Idabooner is the expert loader, but I have spent enough time out there shooting to know its a very precise science. Better have deep pockets though as this is becoming a very expensive hobby.
My 7mm rem mag hits the same at 100 yds out to 230 yds. Factory Rem. 150 gr corelocks. 1" groups