Velocity increase in cold weather???

Styled said:
...The other thing that crossed my mind was that I did crack a new bottle of R22 although it has the same lot number....
Click to expand...

Your old bottle of R22 had probably absorbed some moisture after the seal was broken making it heavier.

When you opened the new bottle of the same lot, the powder was drier and therefore when you weighed out the charge you got a bit more powder for the same weight, thus a slightly higher vel in spite of the colder temp.

This seems like a reasonable explanation to me.

This all goes to hell if the loading was all done by volume of course.

Re. the angle of the bullet through the chronograph: I don't think it's possible to get enough of an angle to cause error to be within the sensitivity range of the instrument. I don't think this would be a factor.
 
My reloading is done with a RCBS Chargemaster calibrated prior to use and each weight checked twice, this load had a SD under 10 so no issue there.

I think it is possible that the powder may have absorbed moisture and was slightly different from the fresh canister.

Any how was at the range with today with temps right at -15 degree's and re-shot this load.

58.5gr @+20deg - 3374fps Avg. (Summer)
58.5gr @-0 deg - 3420fps Avg.
58.5gr @-15 deg - 3370fps Avg.
:p

So two thoughts here.. The load I shot today had no loss of speed as compared to the load I shot in Summer... Or the load dropped 50fps again with the drop of 15 degree's.

I think the load dropped again as some of my other loads shot with R22 dropped today too. I now think its important to get larger canisters of power so that the powder keeps more consistent.

The good thing is that the load was shooting ok with groups at and slightly bigger than 1" at 300 for 3 shots, 5 shots opens it up to closer to 2". I was working on some Nosler 115gr BTips that were grouping just as good.

The only benefit of shooting in the winter is that the barrel cools faster.. thats it.
 
These loads where exposed to the elements in a open lid ammo container on the bench, and did not sit in a warm chamber very long before they were set off.;)
 
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