HST have been very low flash in our use, just like the Gold Dot's--both of which use similar high quality propellants. Golden Saber is generally the worst flash we have seen from major manufacturers.
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9 mm 147 gr +P HST (P9HST4) at 1069 fps:
BG: Pen = 14.4, RD = 0.64, RL = 0.41, RW = 147.5
4LD: Pen = 16.3, RD = 0.59, RL = 0.43, RW = 147.8
9 mm Fed 147 gr HST (P9HST2) at 1005 fps:
BG: Pen = 14.0, RD = 0.65, RL = 0.41, RW = 147.6
4LD: Pen = 16.5, RD = 0.60, RL = 0.53, RW = 147.5
147 +P to left of dime/standard pressure to right of dime
There is NO advantage to 147 +P HST.