Trouble with same load in varying temps. I chronyed a load in 75-80 degrees temps and then using the same load in 30-35 degree temps with close to 100 fps difference. In my shooting app, I can put in the load data that their is 100 fps difference and it will take it and give me a dope with the velocity differences in my rifle, but what if the temp outside is 20 degrees, you keep the ammo in your pocket, and load it in your rifle... Likely the temperature of the powder will not be 20 degrees so your shooting app will be off. In a hunting situation this could end up in a missed animal... Hope this makes sense to you.
Us869 does add a bit of velocity in some chamberings. But when you get to the cooler hunting temps, normally with its temp sensitivity, your often along or below the velocity levels that the other, slower, temp stabile stick powders so for that reason is why I no longer plan to use it. Us869's biggest value is the fact that I can go to almost any sporting goods store and find it. But as you can see, it has it's downfalls aswell.
But I'd imagine the powder will act differently in different expansion ratio chamberings so the only thing you can do is test in your rifle to see what happens and see for yourself if this powder meets your needs.
Another thing I realized that I'd say is a good thing with us869 is it does not heat up the barrel as fast as the stick powders do, which is imagine would save some barrel life!
I would think us869 would be too slow for the edge but I've been wrong before
But anyways, just start at a safe starting point an work up to see how it works. Just be sure not to find a max load in 30 degree temps, and then shoot that hot load this summer in 70-80 degree temps as this will end in a very bad situation!!
Best of luck, Tyler