Railguns: Spaceships vs. Ultra-Tech

In the campaign I'm running, I'm trying to get the group's starship set up. It's a decommissioned military vessel, based on the Independence and Freedom-class Littoral Combat Ships (LCS), that now operates as a container ship. The weapons are no longer on the ship, but I'm trying to figure out what it had on it originally. It's a SM+11 ship, with one Medium Weapons Battery. I have adjusted the battery to contain smaller caliber weapons according to how the tables progress: 1 Medium Battery Weapon = 3 Secondary Battery Weapons = 10 Tertiary Battery Weapons [SS27].



I was planning on replacing the Mk44 Bushmaster II on the LCS (30 mm, 200 rounds/min) with one Tertiary Battery Weapon Very Rapid Fire Electromagnetic Gun. The Tertiary Battery Gun is 16 cm for SM+11 [SS27], and drops to 4 cm for the Very Rapid Fire option [SS29]. Using the errata, the damage in Spaceships for this weapon is 6dx10(2) [errata and SS68] with a RoF of 300 rounds per minute [SS58].



However, I compared that with the 40 mm (= 4 cm) railgun in Ultra-Tech. Its damage is 6dx25(3) with a RoF of 1200 rounds per minute [UT142].



I know that Spaceships takes into account relative velocity, but I think the base damage (assuming no relative velocity between the ships) should be the same. I do see that the TL for Spaceships is 7 [SS68], while the TL for Ultra-Tech is 10 [UT142].



So my question is: which damage and which armor divisor is correct?

Railguns: Spaceships vs. Ultra-Tech