Question for the experts

tpcollins

New member
If a large caliber barrel, let's say .50 muzzleloader, went from room temperature to -20 below zero, what affects would there be to the OD and ID of the barrel, theoretically? Would the barrel OD get smaller and the bore get larger due to the molecules packing close together or what? Thanks.
 

Brian Pfleuger

Moderator Emeritus
Every dimension of a barrel will get larger with heating and smaller with cooling. The difference over such a small range as you mention is irrelevant.
 

Ben Towe

New member
I agree with Brian. Even if you kept dropping the temperature, the steel would become fragile before you saw any relevant diameter changes. At the opposite end of the spectrum, you would see erosion issues due to the steel becoming softer at high temperatures long before you would see relevant diameter changes. That's my opinion anyway. In the temperature ranges you cite, I doubt you would see more than one or two ten thousandths inch change (0.0001 or 0.0002 inch), and perhaps less.
 

MarkCO

New member
Based on a few assumptions for steel type...If you had a 30.000" long barrel at 100F and took it to -20F, it would be ~29.997". If the bore was 0.500000" at 100F, it would be 0.499974" at -20F. The OD would also be reduced in diameter.
 
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