Home Forums Hunting & Shooting Hunting Rifles Temperature vs Velocity - Gun Powder

Interesting data below. Ignition consistency suffers in the cold on average. But that doesn't explain to me, the increase in velocity. Just shows a sloppiness of velocity

223, Dominion small rifle primer (Russian manuf.)
Standard deviation of 27 fps at +7c, and SD of 36 @ -19c

6.5cm, CCI 450 small rifle magnum primer (Lapua brass 147gr ELD load)
SD of 11 fps at -2c, SD 26 fps at -19c

6.5cm, Fed210M large rifle (Alpha brass 130gr TGK load)
SD of 4 fps at +5c, SD of 9 at -19c

6.5 PRC, Fed 210M large rifle
SD of 11 fps at +13c, SD of 25 at -19c (140gr AB RL26)
SD of 9 fps at +10c, SD of 17 at -19c (143 ELDx RL26)

280 Ackley, Fed 210M large rifle
SD of 9 fps at +6c, SD of 14 at -19c (160 AB RL26)
SD of 22 fps at -2c, SD of 25 fps at -19c (165 TGK Magpro)
SD of 8 fps at +10c, SD of 28 fps at -19c (195 EOL RL26)

308 Win, Fed 210M large rifle
SD of 21 fps at +12c, SD of 46 fps at -19c

300wm, Winchester Large rifle magnum primer
SD of 11 fps at +18c, SD of 12 fps at -19c

338-06, Fed 210M large rifle
SD of 10 fps at +10c, SD of 6 fps at -19c (230 ELDx BigGame)
SD of 8 fps at +17c, SD of 22 fps at -19c

375 Ruger, Fed 215 large rifle magnum primer
SD of 7 fps at +10c, SD of 11 fps at -19c (270LRX BigGame)
SD of 16 fps at +23c, SD of 12 fps at -19c (300NP W760)

On average, SD in warmer temp (+9c avg) was 12 fps. In cold (-19c), 21 fps. That's 75% more velocity variation when temps dropped 32 degrees Celsius