Conveyance infusion description inaccurate or vague

I was doing a benefit comparison between the conveyance infusion and the death infusion when I noticed a discrepancy in the description for the conveyance infusion. This could be because the game is not using straight multiplication for damage calculations.

In contrast to the stated 5%, 10%, and 15% increase in ranged damage indicated by the infusion descriptions, when I tested the numbers on a Winchester Rifle with a base damage of 1647, the green infusion increased damage by 1.64% (to 1674), the blue infusion by 2.85% (to 1701), and the purple infusion by 4.92% (to 1728). These numbers were taken from the item description, but not tested on targets.