I'm just going to put this out there. You may want to consider the 185 Berger Hybrid. It is 5grns lighter, and won't give anything up to the 190. It has a G1 BC of .569 and a G7 of .291 which is the same as the 190. You will be able to push it harder, and in my opinion a huge bonus on flattening out the trajectory. After playing with this caliber for 2yrs, its my belief that the 185 is the optimum weight especially now that the Hybrid is available. Also the use of H4350 would be the best powder unless you wanted to get stupid fast with it and use RL17. I will caution that if you use RL17, you'll want to make sure you find an accuracy a little lower than max. When it gets hot, the pressure on that powder will go up. JMHO
As far as your smith is concerned, sounds like your 280AI builder is a good one. If it were me, I would stick with him. Can't wait to see the finished product.
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