Reloading .303 British : VihtaVuori N540 and what I learned

   The test temperature at both sites were 12°F @ Location #1 and 68° @ location #2., a difference of 56 degrees. Elevation @ location #1 is 5003' whereas elevation @ location #2 is 1086', a difference of 3917 feet. (It must be notated here that, the test rounds were left out to acclimate to the ambient air temperature at each location.)

   The test rounds used were .311" 174grn FMJ-BT charged with 40.7grns of the N540. C.O.L. was 3.075" and Federal GM215M primers were used as an ignition source. Averaged FPS @ location #1 was 2442. Averaged FPS @ location #2 deviated by 12-15 fps with NO change in POI at either location. 

Due to the charge weight, it was noticed that an increase of 25-35 FPS can be achieved with the same pressure levels or "slightly lower" compared to that of IMR4895, H4895 or Varget.

     It was concluded that the VihtaVuori N540 is very "Temperature Stable", Clean Burning and can be loaded to give lower pressures  while giving better MV results by maintaining consistent charge weights. 

 The large granular size of the powder can make drops from a volumetric powder measure inconsistent however so, it is worth the time and effort to verify the weight of each charge...