Calvin45
Well-Known Member
Cold air is thicker!!!!You are farther north so air is thinner.
REVERSE TEMP SENSITIVITY????
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RockyMtnMT
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I decided to measure a bullet at 87* and then stuck it in the freezer overnight. Guessing about 0*, no thermometer in the freezer. Bullet lost 3 ten thousands in dia. -.0003"
Interesting, now put your guns action and barrel in the freezer and see what you get. Would be interested to hear.
Nah, I think Steve should hold the rifle to make sure it doesn't get damaged in freezer.
Calvin45
Well-Known Member
I can just imagine my wife's dead serious stare…
"Honey, dear….why is there a rifle in my freezer?"
"Honey, dear….why is there a rifle in my freezer?"
RockyMtnMT
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I'll see if I can get a barrel in the freezer at the shop.
Calvin45
Well-Known Member
Just thought I'd add we raise them that way here haha…gotta be winter tough or you're not gonna have a good time. That being said, my four year old is a psycho like me (4 year olds are just a different breed of human too).
I had told him he wasn't allowed to go outside because he's got influenza and is an asthmatic so running around was a bad idea…the little brat quickly threw on winter boots and ran out the door IN NOTHING BUT A T SHIRT, GITCH, AND A PAIR OF BOOTS!
It wasn't very cold here, -4 c or 24 Fahrenheit. But still. I chased that deranged child around my back yard while He ran through knee deep snow with no pants on laughing like a maniac! Decided experience would be a better teacher and let him find out and stay out yher thinking he'd be right in begging for warmth. The lunatic boy played in sub freezing air and snow for 10 freaking minutes, calmly came back inside, legs and hands glowing red from cold, and never complained once
. Did ask for some hot chocolate.I couldn't tell if I was disturbed, annoyed, or proud of the kid haha.
Fiftydriver
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Its not so much the dimensional changes you see when steel or metal gets cold, its the ability of the steel to move around a bullet being forced down a bore at very high velocities. Colder the steel, the more time it takes for the steel to MOVE when a bullet comes screaming by. As it can not get out of the way fast enough, pressures spike…..
Fiftydriver
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Dont think you will see much dimensional changes with the barrel either. I have tested this with barrel blanks and not seen any significant barrel change. Not more then 0.0002" anyway, the difference in my pilot bushing sizes. The cold just changes the barrels elastic properties more then anything.
Calvin45
Well-Known Member
I see what your saying. If there's anyone whose knowledge I'd trust it's you.
That being said, if that's what's going on why is it so pronounced with only these powders out of what I've tested?
I still think the "pixie dust" has something to do with this haha.
But that's a great point that the dimensional contraction of a material in the cold is not the same thing as reduced elasticity.
Bob Wright
Well-Known Member
FWIW, Reloder 23 is also a powder that can speed up at colder temps, per their customer support tech. I don't live in a climate to really test it.
Calvin45
Well-Known Member
Also a pixie dust powder if you know what I mean. Rl22 slows down hard when it's cold.
If that info came from manufacturer's Rep, I think we have our answer. Pixie dust additives. If the barrel constriction or construction or malleability does anything, I say it's a very minor player. Because I've tested multiple powders in similar temps. Even in the same rifles. Differing powders have had differing temperature vs MV responses.
Powder additives is the major influence on higher velocity in colder ambient temps. Otherwise RL 22 would also speed up in colder temps. And that's simply not gonna happen.
Fiftydriver
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All powder react differently with changes to the pressure curve. Some will increase in burn rate with more resistency while others burn rate may not change much at all.
