Per Vihtavuori, I cannot get as high a velocity as with the 3N38. Per the current online VV load tables, I can get only 1188 fps with the N320, and only at the MAX load that VV recommends. EWhereas I can get 1324 fps with a MIDDLE of the table loading with 3N38, and 1401 fps at the maximum loading if I really wanted to, and still stay under the SAAMI limit (the regular SAAMI limit, not even getting anywhere close to the +P limit).
AND the peak pressure with the 3N38 will be lower since it burns so much slower than the N320. VV designed 3N38 that way to enable high velocities without really high pressures, for Action Shooting competitors who are loading for 9 Major, and who need the long lower peak pressure burn to get there, in fact need burn past the muzzle to drive their compensators.
Plus, the 3N38 at the moderate 8.0 grains loading, fills the volume of the case remaining under the seated bullet, and a full volume ensures the most uniform burn.
Jim G