300 whisper super-sonic load range results

[kurtz]

Went to the range this weekend to test some super-sonic loads and came across something interesting and need some advice….may be a case of reloading basics but I had not picked up on it until recently….I have been working up super-sonic loads using 110 and 125 grain bullets with H110 powder….The brass that I have been using is commercial Winchester formed with Hornady 300 Whisper dies and trimmed to 1.355”…I had hit a max load at 2340fps with the 125 grain bullets and a little over 18 grains of H110, bolt was tight coming out of battery and primer was flat….during reloading I would full-length size the brass and tried different overall lengths to see how it affected accuracy and pressure indicators….over the last few weeks I purchased a neck-sizing die to see if that would help accuracy….not only did neck-sizing the fire-formed brass help the accuracy but I can now drive the 125’s over 2450fps and 110 VMAX over 2640fps with right at 19 grains of H110 and no signs of high pressure, bolt lifts easy and edges of primer are round with no extruding of metal around firing pin strike…..has anyone else seen or is it common for pressure indicators to drop so drastic with neck-sizing fire formed brass?