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....
I would guess (and this is only a guess) is that's another way of stating the term I prefer to use, temperature resistance.
I have yet to test a powder that's absolutely stable at any temperature we might shoot in. Instead, some are stable in a wider range of temperatures, and even within that temperature range some will be more consistent than others.
Just about any smokeless rifle powder made today produces pretty consistent velocities in temperatures from the 20s to 80s, Fahrenheit--which is one reason quite a few handloading hunters claim to have never experienced any "problems" with temperature: Most hunting takes place in that temperature range. This is FAR better than smokeless rifle powders of a century ago, some of which varied considerably within that same temperature range.
Quite a few of today's powders will maintain consistent performance from 70 degrees down to zero, or even lower. In my experience (which in the past quarter-century or so has included a LOT of cold-testing) all the powders advertised as "temperature stable" will do this, as well as a few others not advertised as stable.
Above about 80, however, I have yet to encounter a powder that produces the same velocity, though the ones advertised as stable gain less velocity (indicating less pressure) than others. Of course, this is also affected by the heat of the barrel, which can increase considerably due to both sunlight and shooting--and how long we leave a cartridge in the chamber of a warmer barrel.
Might also mention (again, as I have in the past) that the specific cartridge/bullet application can also affect temperature resistance, as well as how much of the case is filled, powder compression, and the primer.
