[ThunderSleeps]

The only difference between pulling the trigger on Earth and in space is the shape of the resulting smoke trail. In space, "it would be an expanding sphere of smoke from the tip of the barrel," said Peter Schultz an astronomer at Brown University who researches impact craters.

I would expect a better analysis from a University astronomer. An expanding sphere? Hardly. The gases and smoke particles produced by the combustion in the weapon are going to expand down the barrel. In so doing they are going to accelerate to a pretty good velocity. (eg. rifles typically a couple thousand fps) upon exiting the barrel there is no atmosphere to slow the gases. The only significant force acting on them is their own molecules pushing on each other. So they will begin to push apart and expand, while still retaining their significant velocity. The resulting smoke trail should resemble a large cone, not a sphere.

[Atlas Sneezed]

The resulting smoke trail should resemble a large cone, not a sphere.

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Thank you. And the front of the cone might be spherical. The “sides” of the cone would likely flare outward. to a limited angle. And there’d initially be a “hole” in the center of the cone due to the bullet blocking the initial gases.