Greetings!
For DropShips, the BV rules (TM, 6th printing, p.312 or BV errata, 4.1) say to find the arc with the highest weapon BV (step 2), the nominal "Nose". However, the rules don't say anything about choosing that arc when there is a tie.
When the nose and aft BV are equal, the adjacent arcs for step 4 are the wings for nose and the aft wings for aft. When for step 2 the wing and aft wing are equal, either the nose or the aft would be included as adjacent in step 4.
An example for the second case is the Cargoking (TRO 3026 Revised, p.118, aka Cargo King 2790 in MegaMek). The aft and nose are not equal in the Cargoking and as the "Right" arc they would get added at either x0.5 or x0.25 depending on heat, whereas as the "rear" arc they would be fixed at x0.25. This seems to allow two different BVs depending on the choice of "Nose" arc (when the unit is heat efficient for the "nose" and "left" arcs).
So, as a question, if I'm not mistaken about this, how is the choice for "nose" arc to be made in case of a tie between locations that aren't tied by wing symmetry?
