Varminterror
Member
- Joined
- Jul 17, 2016
- Messages
- 16,088
Surface area grows in proportion to the square of the linear dimensions. The mass/volume grows in proportion to the cube of the linear proportions.
This isn’t true for the case of rifle barrels. We’re not talking about squares and cubes, or circles and spheres here. Check your math/geometry, because this is WAY off.
If you double your length, 2x linear dimension, you double your area. If you double your diameter, you double your surface area. Recall - external surface area of a cylinder: A = pi * D * L. So doubling diameter doubles area, nothing more.
For volume/mass of a rifle barrel, doubling length doubles volume/mass, doubling diameter doesn’t even quadruple the volume/mass. They aren’t cylinders, they’re annuluses. Recall - volume of an annulus, which is the same as the volume of a large cylinder, minus the volume of a small cylinder: V = L * pi * (OD^2 - ID^2)/4. If the ID of the barrel is unchanged, then doubling the OD only increases the value of the OD^2 term by 4x. So if the ~5” of 0.64” diameter barrel between the tapers of a Government profile barrel increases by 56% to match the 1.0” diameter of the Hbar profile (D2 = D1 * 1.56), you only increase the relative volume of that section by 164% (V2 = V1 * 2.64), which is a power factor of 2.19, not the cube. In other words, for that particular increase in diameter, the proportionality between diameter increase and volume increase is NOT the cube of diameter ratio. The volume increase is proportionate to the diameter increase to the 2.19th power.
So, without intent to be insulting, your math which lead you to believe doubling diameter lead to 4x and 8x and your belief that result means smaller diameter barrels cool faster is wholly incorrect.
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