Complex sentence: Another reason is that it is not possible to fire accurately out of the ports of a moving IFV and access to firing ports would require internal stowage to be moved from behind the seated soldiers in the rear of the vehicle.
Split into simpler sentences: Another reason is that it is not possible to fire accurately out of the ports of a moving IFV. Also, access to firing ports would require internal stowage behind the seated soldiers to be moved to the rear of the vehicle.