depends on your humidity situation, the double cases as described are very good in fact we use em for shipping our custom guns in HOWEVER if there is any moisture in the air the foam/plastic will trap it in with your gun as they don't breath at all, we usually put the custom stuff like AKs and FALs ARs G3s etc... in a gunsock then a plastic sleeve over it we then put a shop vac on the plastic sleeve to suck out all the air then seal it prior to placing it inside the hard case for shipping as we cannot control the enviroments it will be exposed to and dramatic temperature changes in a semi trailer etc... while en rout before going to these extra steps guns would arrive with minor surface rust to destinations in some parts of the country. I own a trucking company and it did not take me long to figure out what was happening.... they all arive perfect now.
Depending on where you live ya may need to at least add a gunsock as well as some dessicant packs inside the case just for added protection...