If it's anything at all like a B737 freighter, the forward cargo door plus a bulkhead tends to bias to a forward CG in a vast majority of loads. Very forward, in some cases.
Flown empty, or with light loads, or with a container load each with similar masses, a ballast container aft is required to achieve an in trim configuration.
With a cargo net instead of a bulkhead, the forward CG is alleviated.
Add the longer fuselage of a -400, and you start to encounter greater considerations of fuselage bending (Banana).