Reloading & temperature

BRACES of Bristol - Mauser M12 with Schmidt & Bender 2.5-10x56 Illuminated Scope

243 Stalker

Well-Known Member
The last batch of bullets I made up was a couple of months ago when the temperature was about 10 DegC. In this hot weather (30 DegC) I was wondering if temperature variation makes a difference when reloading, such as resizing brass etc and if this has an impact on accuracy?
All comments welcome.
ATB 243 Stalker
 

charadam

Well-Known Member
The Coefficient of linear expansion in brass is around 18.7 10[SUP]-6 [/SUP]m/m / deg K.

The 20 Dec C (same as K for all practical purposes) temperature difference you quote would result in 20 x 18.7 x
10[SUP]-6 [/SUP]mm.

In round numbers, a 55mm long case would expand in length to 55.0198mm. (.0198mm =
0.000779in).

Not enough to worry about IMHO, and probably not measurable given the average reloaders' resources.

Of course it shrinks back to 55mm at 10 Deg C.


 
Last edited:

j0e_bl0ggs

Well-Known Member
The last batch of bullets I made up was a couple of months ago when the temperature was about 10 DegC. In this hot weather (30 DegC) I was wondering if temperature variation makes a difference when reloading, such as resizing brass etc and if this has an impact on accuracy?
All comments welcome.
ATB 243 Stalker
your only real concern is if you have a hot [max] load that was worked up in a low ambient temperature using a temperature sensitive powder. Brass expansion etc is of no concern.
 

243 Stalker

Well-Known Member
Charadam - thanks for the reply, can rule expansion out.
Joe - my load is well within the limits so no worries on it being a hot load.

I am interested in peoples views if temperature deviation has an impact on reloading or if anyone has experience of it.
ATB 243 Stalker
 

Cooter

Well-Known Member
Charadam - thanks for the reply, can rule expansion out.
Joe - my load is well within the limits so no worries on it being a hot load.

I am interested in peoples views if temperature deviation has an impact on reloading or if anyone has experience of it.
ATB 243 Stalker

Some powders are affected by the ambient temperature more than others.

I found Varget is stable/consistent at most temperatures where a change of 15 C can have an impact on Vhit powders.

I used to run a target load of 60grn V Max at 0.75grn under the max load with N133. I found that it showed pressure signs in hot weather, the POI shifted by over an inch and the groups opened up.
To resolve the problem but maintain the POI where I wanted it I dropped the charge by 0.5grn in hot weather, which wasn't much but it removed the pressure signs.
In cold weather the same load shot 0.5inch low, but the groups were excellent.
 

MarinePMI

Well-Known Member
Warmer temperatures always affect my reloading.



Namely, I don't want to sit in the garage and reload in the summer heat, so the heat affects my reloading by encouraging me not to do it! :D
 

243 Stalker

Well-Known Member
Marine - that is exactly why I got no further than resizing this afternoon as the temp in the garage became intolerable and thus the idea for the posting of this thread began.
​ATB 243 Stalker
 

Tackleberry270

Well-Known Member
My reloading room is lovely and cool being under the house and thick stone walls. Only problem is it still needs a heater to keep the damp out. I love Varget for being consistent in temperature changes. I don't have time to be creating new loads for different seasons! Luckily I have quite a few tubs to keep me going.
 
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