So MD, what does Alliant mean by “controlled temperature stability” and “provides a consistent, controlled response to temperature changes”? Not temp insensitivity? Asking for a friend....
When I talked to Alliant and asked that question the tech guy said that RL-26 will generally show a velocity loss as temperature drops, but does so in a linear fashion, and conversely, velocity will increase as temps increase. Temp sensitive powders will often show a sharp drop in velocity at some temperature threshold, usually that is in the low teens or single digits in my experience. What I originally learned from some guys who did a LOT of temp testing of powders beginning in the 80's, that it's usually when temps hit single digits one sees a significant drop off in velocity. But, accuracy may suffer even before velocity shows a decrease.
I have temp tested RL26 a number of times now with a 270 and 150 NPT's at 75-80 degrees,, at 35-40 degrees, at 8-15 degrees, and have tested two different lots (but not at all those temps), and it does show some temp sensitivity in my tests. The velocity loss isn't big, 25-35 fps, but is outside of the margin of "error" that will happen when chronographing shot strings at different times. But the accuracy still seems to be there.
What has messed me up on following this up is that with three different lots of RL26, each lot has been successively slower. Lot three is 60-70 fps slower in two different 270's than the first lot.
