Skinwalker Prime BV Calculations
To start with, I noticed the Skinwalker BV discrepancy while entering it into third-party BattleMech design software, which normally puts out the exact same BV as you publish. I then repeated the BV calculation in Excel, and came within 11 BV points of the software. I did not include modifiers for effective improvements to both piloting and gunnery skills.
I may have made a mistake, left out the PA(L) or armored component value for the cockpit, or perhaps some of the factors have been adjusted in dev-level errata...?
In any case, here are my calculations for the Skinwalker Prime:
Defensive BV:
Armor Value (161) x 2.5 x Ferro-Lamellor (1.2) = 483
Structure Value (91) x 1.5 x Endo-Steel (1) x Clan XL Engine (0.75) = 102.375
Gyro ('Mech tonnage) x factor (standard gyro factor according to IO, p. 193, "Gyroless 'Mechs" - 0.5) = 27.5
Defensive BV before Movement Mod = 612.875
Movement Mod for run of 9 (+3): 612.875 x 1.3 = 796.7375
Total Defensive BV = 796.7375
Heat Efficiency: 6 + 13 DHS - 2 (movement) = 30
Clan Cumulative Weapon Heat/Cumulative BV tally:
2x LPLs 20 / 530
2x MPLs 28 / 530 + 222 = 752
2x SRM6 Ammo 28 / 752 + 14 = 766 (note, Ammo BV would have been capped if exceeding weapon BV)
1x SRM6 32 / 766 + 29.5 = 795.5 (half BV because it is over Heat Efficiency)
1x SRM6 36 / 795.5 + 29.5 = 825 (half BV because it is over Heat Efficiency)
(Above Heat Efficiency)
Total Weapon BV = 825
No other equipment = 0
Add 'Mech tonnage = 55
Offensive BV before offensive Speed Factor = 880
BV x Offensive Speed Factor (1.5) = 1320
Total Offensive BV = 1320
Total Defensive BV = 796.7375
Total BV before multiplying by interface cockpit BV factor (IO, p. 193, "BattleMech Interface Cockpit") = 2116.7375
BV x Interface Cockpit BV factor (1.3) = 2751.75875 = 2752
(For comparison, published BV is 2809, and SSW 0.7.4 and 0.7.6 generated a BV of 2763)