Re: Load Developement ???
At this point, I would stick with the H1000 or try some Retumbo. They are more temp stable powders than R-25
I do think it is important to find your upper limit of pressure. Keep the ammo warm in your car if you are concerned about a pressure spike in warmer weather.
Since you have already done some load work, it shouldn't take to much more work to find your upper pressures.
After that back off on charge weight alittle and try some groups. Then try some loaded at different distances off the lands, and into the lands no more than .005 if this is a hunting rifle. Say on lands, 0.020/0.050/0.070
See what groups best for you. Or, load different charge weights, but all at the same distance from the lands, and see what groups best for you. But only change one factor at a time.
The reason I use a chrono when load developing is to see at what point I don't see anymore velocity with more powder. There is no sense in loading more powder if you don't get much return for it. The other reason is to see what my ES is.
I need a low ES for tighter vertical at longer distances.
I would be looking for 1" groups at 200yds.
Also, if you are shooting in the snow, on the ground, that is more difficult than on a nice summer day, so your groups might not be as tight.
If you are happy with what you have when you posted, find a place to shoot at 300 to see what your groups are like.