Why does muzzle velocity increase with barrel heat?
Increased pressure.
Lol. In a semi auto, or a full auto, the rounds are ambient temp if fired rapidly. When I was shooting the M60, and it was hot, a cook-off was pretty common.
I doubt most on here have put that many rounds through a barrel.
Like has been said, the barrel expands in two directions. Inward and outward. Its not much, but it will make a difference.
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