Clays temperature sensitivity - Velocity loss cold weather?

[alecmc]

Just curious about everybodys personal experience with clays and how temperature sensitive it is in cold weather.

I recall last summer making a major load last summer that was around 170ish

now in the winter, today at 32 degrees F, I am slightly below, around 160.

Is it typical to loose that sort of velocity with major temp swings ?

Thanks

[alecmc]

bump?

[pskys2]

Might be a bit extreme. But combine differences with lighting, which can easily show a 30+f/s swing and the normal drop of velocity with Clays as it gets colder and you can see it.

Clays definitely loses velocity as it gets colder, but at normal pressures it's usually less than that.

I have seen it drop like that when I tried to cut it too close.

For instance I've loaded test rounds at 80 degrees with 4.2 clays and a 230 bullet for a PF of 168. Then loaded up a bunch and found the powder drop was running a .10 lower than I wanted and the PF was 165. That can happen from either an actual shift in the bar or a different can/lot of powder or even using the same lot after several months of being open and sometimes the density of the powder seems to shift. Then took it out in 20 degree weather and the PF was 162.

I usually set a Powder Bar for my Match Loads, lock it with a set screw, and leave it alone. By doing that I've never had an issue with the powder drop causing velocity drops.

One reason I always try for a PF of 173+. Gives me a bit of a fudge factor.

Edited February 9, 2013 by pskys2

[Reinz]

Just curious about everybodys personal experience with clays and how temperature sensitive it is in cold weather.

I recall last summer making a major load last summer that was around 170ish

now in the winter, today at 32 degrees F, I am slightly below, around 160.

Is it typical to loose that sort of velocity with major temp swings ?

Thanks

Clays is my main powder that I've been using for years.

That is exactly what I would expect with that kind of extreme drop in temp.

Switching to Mag primers made a huge difference for winter time.