You all are correct about the 'normal' differences between season-to-season variations in the UK and in AK. The matter of sound absorption by snow both falling and on the ground is also very real, and I suspect maybe even more noticeable when using a moderator (I wish I could find out about that first-hand
).
I also read about the "insensitivity" of Hodgdon's "extreme" powders. However, when I actually tested a couple of them, I found no
measurable difference between the "new" powders and the "old" ones in terms of temperature "sensitivity"
as the temperatures fall. I'm not averse to calling 'a spade a spade' but I hesitate to do that until I know the truth for a fact, and know that someone
knowingly lied. I'm not
sure Hodgdon lied about the lack of temperature sensitivity of their new powders for two reasons:
1) Most of the temperature issues in the US and Africa are "hot" ones, not cold ones. (More about that in a moment.)
2) The powder ALONE may be relatively "insensitive" to temperature (More about that too.)
With regard to "1" the complaints of most shooters/reloaders/hunters in the US are related to shooting Prairie Dogs in the summer, and going to Africa and experiencing really hot temperatures relative to where they came from in the States. I suspect (but don't know) that Hodgdon focused on changes in their powders that dealt more with increases in ambient temperature than decreases in it. One might expect the chemistry of powder burning to be uniform with temperature as the temperature goes up or down. However, not knowing what method(s) Hodgdon's used for achieving their reported insensitivity we can't know if it is some process that may mitigate variation as temperature rises from "normal" temperate zone values as opposed to having a linear response across temperature. (Meaning it responds the same regardless of the direction of change.)
With regard to "2", I'm not sure that the
effect of a 20C change in temperature is the same on the system that a rifle is as temperature goes up and down. For example, let's suppose that there is some point at which a movement in metal results in some 'threshold' or 'cascade' effect. Up to that threshold, the effect is unmeasurable. Beyond that point the effect is significant. I can imagine that as long as the bullet is sealing the bore, the effect is marginal, but once the barrel and bullet differ sufficiently to allow gas to blow by the bullet, the effect is substantial. I'm not saying this IS what is happening, I'm simply offering an easy-to-explain example for why going one direction in temperature change might be different than going the other.
I don't KNOW what the reason is that the new, supposedly temperature insensitive Hodgdon powders I have tested haven't been "insensitive" to falling temperatures, but I know that they haven't. When I shoot all the various powders I have at temperatures below 0C, "things change" at the target butts and across the chronograph. In fact, the only "dud" I have actually experienced in over 42 years of reloading was at the range on a 0C day using the very large case of the .50 Alaskan and "only" a large rifle primer. The 'cure' was simply to go to a "magnum" primer. Now THAT is PURELY a "chemistry" matter, but it was also PURELY a
function of temperature as well.
I'll close by repeating that the BEST way to get THE answer is to 'pull the trigger' and
measure the changes if any. AND,
that is a "good thing". It means finding out something about your rifle FIRST HAND, and not having to wonder if your particular rifle isn't "just a little different" than someone else's rifle that told you to expect "this" response.
Paul