20 degree? (no sign of pressure at 20 degrees) AT 20°F, and then there is the Tea Cozy,
http://en.wikipedia.org/wiki/Tea_cosy
The secret to successful ice fishing is ‘keep your worms worm’ if a reloader wants to know what effect reloading in warm weather will have in cold weather, keep your ammo warm, carry your ammo to the range in an insulated/warm container, heat up some bricks, place them in the bottom of a cooler, use a thermostat, purchase the infa-red $27.00 dollar Harbor Freight/battery powdered temperature checker. When at the range fire the rifle a few time to get the operating temperature up to speed, then start the test.
I have heard it all my life “I am going to Colorado and I just do not know what effect the cold weather is going to have on my ammo”, develop loads for cold weather, develop loads for warm weather and develop loads for hot weather, then there are powders that are effected by temperature. The British made an attempt at replacing the 303 British round with a round that was said to be similar to a Ross round. The round was not suspect, the rifle needed improvement, but, the British was/did not change the powder, the powder cooked off before the trigger could be pulled and the barrel did not last long, pressure? was off the chart.
Though Winchester/Browning was a just a buggy ride down the pike from Springfield, Springfield thought they were the only makers of fire arms, and the English never heard of DuPont,
Even though one of the DuPont's went to Europe to learn the process for making smokeless powder.
http://ezinearticles.com/?Sales-Trai...les&id=1369924
F. Guffey