In fact, what you will see if you look at the innards of both types of ammeters, is that they are constructed similarly. A coil through which runs a current, which creates a magnetic field, and a little magnet connected to the spring-loaded needle reacting to that field. (Or the magnet is fixed and the coil connected to the spring-loaded needle - the effect is the same.) Plus a shunt to handle the majority of the amps. The difference between both types is simply the position of the needle when there is zero current.
Ammeter - Wikipedia, the free encyclopedia
In a pinch you could probably swap one type for the other and still get more-or-less meaningful results. If you know how they work that is, and where they're place in the electric system. And if the needle doesn't deflect beyond the scale.
And that would definitely not be an approved solution of course.