[FF&S] Comparing small arms to artillery in a borderline case

[Vespers War]

According to Fire, Fusion & Steel, weapons 20mm or smaller in caliber should be treated as small arms, and anything larger as artillery. I decided to test this with the 1" Gatling Gun. As a late 1800s weapon, I decided to make it as a TL 4 weapon. It has a caliber of 2.54cm, 33" barrels, and uses 500 grains of black powder as a charge.

As a small arm using Black Powder Conical ammunition, the 1" Gatling has Dam 6, Pen 2-3-Nil, and a short range of 167 meters.

As an artillery piece with Kinetic Energy Armor-Piercing rounds, the 1" Gatling has Dam 6, Pen 1/1/1/0, and a short (direct fire) range of 278 meters. It also has a HE round at Dam -1, Burst 5, Pen Nil.

The real-world weapon, on its carriage, massed 2210 pounds, so recoil isn't an issue, and ROF would be 5. This Gatling still used the open ammunition hopper rather than a fixed feed system, so it can be reloaded by an assistant while the gunner is firing.

The surprise to me is how different the ranges are, though I suppose that could be from using Black Powder (from World Tamer's Handbook) for the small arm. I haven't tried working out the numbers for a straight-walled smokeless round of the same size.