DS2: Artillery ammo design question

My question is: how much free space for ammo do you get when you by
an artillery weapon?

Arty design on pg. 12 says you get room for ammo.  Artillery takes 4
spaces per load.  I can't find it explicitly, but the rules seem to me
to indicate that you get space for 3 loads of ammo.  That's 12 free
spaces of ammo in my class 2 APC lugging around a light RAM mortar.
That seems a little much.  Can someone correct me?  (Yes, I bought
some new toys^H^H^H^Hmodels today)

To me, it makes sense for the above vehicle to be able to carry more
than one effective round of ammo, so it seems right to allow 3; it's
the space points that are bothering me.  Plus, I want to make sure the
new design page does it correctly.

Thanks.

--
Andrew E. B. Cowell <cowell@cs.utk.edu>
http://www.cs.utk.edu/~cowell/