I am considering building a 7WSM specifically around the 162 A-MAX (.625 BC) or Berger 168 VLD (.643 BC) and 1-10 twist barrel. I want to maximize the powder capacity (and velocity) of the case, so the plan is a cartridge overall length based on these bullets seated to a maximum .284" into the case neck (or less - what is the minimum I can get away with ??). I will also have the barrel/chamber throated so that the bullets would touch the lands when seated to this cartridge COL. Lastly, I do want to use the magazine of the rifle. I suspect I cannot use the magazine on a short action with this proposed COL (whatever that may be - not sure at this point - anyone ??). Therefore, I am considering custom chambering a new long action SPS or Savage 110 (in 300 RUM as a donor action?) to this cartridge spec. Any problems I may be getting into with this build ? Can I expect much of an improvement in performance over a short action with these bullets seated to 2.86" COL ? Any advice or thoughts would be appreciated.