Looking to develop load on Berger 180 for 7mmRM. VLD, still hoping to get some Hybrid's. What should come first, Powder charge or Seating depth? I would really like to use Extreme, so plan to start with Retumbo unless other's overwhelmingly disagree? If I am right to start with Retumbo, then I think basically getting on target and then testing groups at say 200 yds(or farther, wind permitting), for 3 shots each at seating depth of +.010, +.050, +.090, and +.120 and go from there? I would usually simply pick 1gr below a safe "max" charge. Alternatively, I go with a starting seating depth of +.010, and do a latter test at say 600yds? Seems hard to want to do a long distance latter test unless I know the inherent accuracy of my bullet/powder/seating combination to best assess results at distance. I don't have the experience most on here do, but I have rarely found that a certain load that will eventually show promise, won't shoot well approx 0.5-1.0gr below max. PS My mag should be able to seat quite long on new gun. Gun should be accurate, but I assume even the best gun has loads it will dislike.