There are MANY conditions that can cause pressure issues.
Elevation, humidity, ambient temperature, ammo temperature (yes!!! - prairie dogs above 90 degrees F provides great fun if you keep your ammo in the cooler - no kidding), OAL, case capacity, primers, etc, etc, etc. Literally, there are no less than 100 "normal" variables that can contribute to pressure in ANY caliber.
Even two rifles, manufactured back to back, can be particular about what load they shoot best and when pressure signs arise. Treat every barrel as a new girlfriend - find out how/what she likes....and condition your dating plans (reloading plans) accordingly.
I built two 6.5x55 AI's with barrels from the same manufacturer. Same reamer cut both chambers on the same lathe, by the same person. One barrel is 50 - 75 FPS faster than the other....and a hair bit more accurate. Of course, the faster/more accurate barrel was my shooting buddy's barrel...not mine. :)
Use a MAGNUM primer with the slow burning powder. I like Remington, CCI, Winchester, or CCI.
....and...remember...the loads you work up in 20, 50, 75, and 90 degree temps are ALL different and will perform differently if shot at other temps then when developed.
Bookmarks