W231/HP-38 is temperature sensitive which means your loads will chrono faster on warmer days. Due to this reason, many match shooters needing to meet 125 power factor will use higher powder charges in winter or simply load to higher 130 PF. It is also why many match shooters use Titegroup, which is less temperature sensitive than W231/HP-38, with less/no need to adjust powder charge to meet PF.
Here are chrono number difference between 56F and 79F:
115 gr RMR HM RN 4.8 gr W231/HP-38 @ 1.130": 1275-1263-1253-1290-1248 fps (56 F - JR carbine)
115 gr RMR HM RN 4.8 gr W231/HP-38 @ 1.130": 1303-1289-1298-1311-1323 fps (79 F - JR carbine)
WSF is reverse temperature sensitive which means your loads will chrono slower on warmer days. I am finding that Promo may be reverse temperature sensitive -
https://www.thehighroad.org/index.php?threads/is-promo-reverse-temperature-sensitive.808919/
100 gr RMR HM RN 4.5-4.7 gr Promo @ 1.050": 1478-1475-1480-1471-1467 fps (58 F - JR carbine)
100 gr RMR HM RN 4.5-4.7 gr Promo @ 1.050": 1458-1450-1445-1442-1448 fps (71 F - JR carbine)
Here's a listing of temperature sensitivity of powders -
https://www.thehighroad.org/index.p...s-and-discussions.778197/page-7#post-10117881
Standard/Temperature sensitive powders (produces higher velocities at higher temps):
- Clays
- Titegroup
- W231/HP-38
- Power Pistol
Reverse/inverse temperature sensitive powders (produces higher velocities at lower temps):
- Competition
- WST
- Promo (Doing more testing to verify)
- Solo 1000
- N320 (but some claim normal temp sensitivity)
- SR7625
- Universal
- WSF
- Silhouette