[kjamma4]

I don't recall that rule.

If it does exist, I'd disagree with it as, in my opinion, it really serves no purpose. The construction rules go into great detail down to the weight per shot so let someone take how ever many shots they want. They are paying the cost and weight of the weapon to begin with and if they feel 17 shots of MG ammo is better than 20, so be it.

There is always a tradeoff in weight, space, and cost so shorting ammo is a good idea to make weight/division - until you have your opponent on the ropes and realize you really could have used those three extra rounds!