I am new to reloading and want to know how to develop a load for my 7mm Remington Mag, with an emphasis on how to deal with virgin brass. I have determined that I have safe pressures in once fired Remington brass with H1000 from 66 to 69 grains using Berger 168’s. I have a Redding Instant Indicator and have determined that my longest twice fired case is right at SAMMI min specs (chamber). Most of my fired cases are around .002” less than SAMMI min as a point of reference, but they range from .004” to .000” less than the min. I am assuming at this point that my chamber is close to the SAMMI min. My new Nosler brass is .015” less than SAMMI min. Should I continue straight to seating depth using the method described in Getting the Best Precision and Accuracy from Berger VLD bullets in Your Rifle or should I fire form my cases first? My understanding is that pressures will be different between new brass and once fired brass. If I do fire form my cases, what is the best method? What difference in accuracy should I expect comparing new brass to once fired brass? I am still getting variation in head space for once and twice fired brass. How do you get the most consistent headspace without having to bump the shoulders back excessively? I am using Redding S bushing full length sizing die and competition seating die. Factory Remington 700 7mm Mag, 24” barrel. Thank you everyone for all of your postings. I was able to get a .6” (edge to edge) 3 shot group with my 66 grain load .010” off the lands on my first reload, which is my best group so far.