Lacking ammo is not cause to say the unit is over valued in BV. It merely points to a design flaw in the unit. Units such as the T-Wolf Prime were theoretically designed for clan style warfare where a limited amount of ammo is actually an asset in many cases. Weapon BV does not take into account durability as part of its calculations. Trying to make it do so is an exercise in futility.
Low ammo forces you to limit your shots and cuts down on the performance of the 'Mech. For example, that Timber Wolf Prime cannot afford to use its LRMs at long range due to the low ammo so you cannot get the full value out of the weapons. The most obvious example of this problem is that you can mount a weapon with no ammo at all which will still cost you full BV despite the fact that you get absolutely no benefit from it.
Now, that is not to say you would need to give penalties from a huge number like 20, but I think it would work to have BV start dropping off if you were below about 10 rounds. It might also be beneficial to give different thresholds for short and long ranged weapons (maybe 6 and 12 respectively) because you tend to need less ammo for short ranged weapons. Another option would be to add an ammo count modifier to weapons based on how much ammo they have instead of attaching BV directly to the ammo, but this would likely require some more intricate math because you would want them to approach the value of energy weapons asymptotically as ammo count approaches infinity which would require an exponential function (you would also need some kind of modifier for the risk of explosive ammunition).
OTOH there is some merit to the suggestion that taking the square root of the product of the OBV and DBV is more accurate that adding the values together. At the very least I hope some play testing occurs in this area with TPTB. I realize that a mathematical calculation of this type by hand would be time consuming but any pocket calculator in existence can do it with ease let alone any advanced calculator program or app you can use on pretty much any PC, tablet or smart phone.
Yes, this is by far the biggest shortcoming of the current BV system and it is really not that hard to fix. Sure the math is slightly harder, but the point of BV is balance, not ease of calculation (the devs do it for us on all canon designs anyways) and a square root is not that hard to do.
The other big issue is with piloting skill modifiers which do not change for different units which draw different levels of benefit from them (the obvious case here is ASF vs. tracked vehicle). The other half of this is that equipment modifiers like the Small Cockpit do not match up with the equivalent skill modifiers which can allow you to pay different amounts of BV for the same net effect.
How would you use a ranged Clan unit like a Supernova or Warhawk on such a small map? The Inner Sphere could run into your short bracket within 2 - 3 turns. Small maps (32 x 34) don't work for Clan games; they inherently favor the Inner Sphere or the side with brawlers. For what reason would a larger map (48 x 51) be "too big"?
Actually, the big assaults do less badly than most on the smaller maps because they do not really loose much because they were not planning on moving much in the first place, although they are still worse off than designs like the Kodiak. The real losers are the skirmishers like the Viper B which want to hold the range open so they can work over the enemy from a safe distance but cannot due to the artificial confines of the map.
Just out of curiosity do you play clan vs I/S games?
Again, I know people are saying here that the clans should be winning but on Saturday I kicked the living snot out of a dodgyy-dodgy-weavy clan guy who was using cover, running like a madman and trying to keep range. Running from a MASC Berserker with a big hatchet is not so easy especially if he's on a suicide charge because and here's the crux of the matter - the IS guy can take a ton more damage than the clanner, but the clanner cannot afford to get hit.
You have yet to tell use how big a map you are using. If you were playing on an appropriately sized battlefield you should have been able to easily outmaneuver that Berserker and make it little more than a waste of BV.