Well this started out as a quick test of two rifles I hunt deer in November with, to see how sub zero temps effects the load specs. I grabbed my 280 Ackley and 6.5 PRC rifles & ammo, and set them outside for hours at -16c (3F) Also had a few rounds of 6.5 Creedmoor I wanted to blow off so set it outside as well. Rifles were really cold, transported to the testing grounds with the heater off in the truck (thank goodness for heated seats). Rifles set in back of truck as I got ready to shoot. -16c (3F) with gusts up to 30km/hr (19mph) Nasty!
My 280 Ackley load is the 160gr Nosler Accubond over 60.0grs RL26. Speeds in the +15 (59F) to -1c (30F) temps I have shot the load at were all in the 2951-2961 fps. Set up the radar, temp -16c (3F) I was pretty surprised when the radar flashed 3100 on the first shot. Five shot average 3057
Next I grab my 6.5 PRC, loaded with 140gr Nosler Accubonds over 55.6grs RL26. Speeds in the +13 (55F) to -5c (23) temps have been 3049-3038 fps. Five shot string at -16c (3F) = 3047. I was expecting less, but now that two rifles with two loads of RL26 didn't lose any velocity in cold temps, had me really thinking. Was expecting below normal speeds.
Now onto the 6.5 Creedmoor. Ammo was 130gr Sierra Tipped Gameking over 42.0grs RL17. Only have shot the load once prior, in +5c (41F) and it did 2749 fps. RL17 is known to be temp sensitive, so I was expecting this one to give 2700 fps or less at -16c (3F) I was surprised when it did 2809 fps! I'd expect that on a hot summer day, not in a nasty winter blizzard.
Back to the 280 Ackley. I had some 165gr Sierra TGK loads done up with Accurate Magpro. Another temp sensitive powder, that should lose velocity in cold weather. In -2c (28F) temps it did 2800 fps. At -16c (3F), 2825 fps
Back to the 6.5 PRC, another RL26 load, but with the 143gr Hornady ELDx. In +10c (50F) to +6c (43F) temps of early summer, it did 2929 to 2942 fps. At -16c (3F), five shot average was 2920. Stable! And a little slower than before, as I would expect.
Back to the 6.5 Creedmoor, 147gr ELD over RL26. I shot this load earlier in the winter at -2c (28F) and it did 2524 fps. At -16c (3F) it did 2546. Another cold weather spike.
One last load to try, in the 280 Ackley. 195gr Berger over RL26. Speeds in +10c (50F) / +7c (45F) were 2655-2674 fps. At -16c (3F) 2692
Cold rifle, did the bore diameter shrink? Causing more PSI? On 5 of 6 loads, I got more speed in the colder temps. I went home and set 8 rifles & ammo outside in temps dipping down to -30c (-22F) , when I shot the next day it was -19c. (-2F) I needed a larger sample size for a retest
My 280 Ackley load is the 160gr Nosler Accubond over 60.0grs RL26. Speeds in the +15 (59F) to -1c (30F) temps I have shot the load at were all in the 2951-2961 fps. Set up the radar, temp -16c (3F) I was pretty surprised when the radar flashed 3100 on the first shot. Five shot average 3057
Next I grab my 6.5 PRC, loaded with 140gr Nosler Accubonds over 55.6grs RL26. Speeds in the +13 (55F) to -5c (23) temps have been 3049-3038 fps. Five shot string at -16c (3F) = 3047. I was expecting less, but now that two rifles with two loads of RL26 didn't lose any velocity in cold temps, had me really thinking. Was expecting below normal speeds.
Now onto the 6.5 Creedmoor. Ammo was 130gr Sierra Tipped Gameking over 42.0grs RL17. Only have shot the load once prior, in +5c (41F) and it did 2749 fps. RL17 is known to be temp sensitive, so I was expecting this one to give 2700 fps or less at -16c (3F) I was surprised when it did 2809 fps! I'd expect that on a hot summer day, not in a nasty winter blizzard.
Back to the 280 Ackley. I had some 165gr Sierra TGK loads done up with Accurate Magpro. Another temp sensitive powder, that should lose velocity in cold weather. In -2c (28F) temps it did 2800 fps. At -16c (3F), 2825 fps
Back to the 6.5 PRC, another RL26 load, but with the 143gr Hornady ELDx. In +10c (50F) to +6c (43F) temps of early summer, it did 2929 to 2942 fps. At -16c (3F), five shot average was 2920. Stable! And a little slower than before, as I would expect.
Back to the 6.5 Creedmoor, 147gr ELD over RL26. I shot this load earlier in the winter at -2c (28F) and it did 2524 fps. At -16c (3F) it did 2546. Another cold weather spike.
One last load to try, in the 280 Ackley. 195gr Berger over RL26. Speeds in +10c (50F) / +7c (45F) were 2655-2674 fps. At -16c (3F) 2692
Cold rifle, did the bore diameter shrink? Causing more PSI? On 5 of 6 loads, I got more speed in the colder temps. I went home and set 8 rifles & ammo outside in temps dipping down to -30c (-22F) , when I shot the next day it was -19c. (-2F) I needed a larger sample size for a retest
