Limiting by space isn't going to work, as they player won't be able to plaunder anything
Side note: If your ammo takes up cargo space, free cargo space won't be checked to see if it fits.
MaxAmmo might work if I set the max to 0, though I think selling the weapons might be a problem.
See, the ammo is invisible. It's there for the weapons modes trick. Ammo is swapped to correspond to the current mode of the weapon. The unforeseen problem is that I'm able to plunder ammo for modes that are supposed to be unavailable.
I seem to remember that if a weapon has a MaxAmmo property, then you can't sell the weapon until you first sell the ammo. As the ammo is invisible, you can't sell it.
I'll have to check outfit limits.