Plastic box might be a nice short term solution
, but the purpose of dimensional lumber and a real live wooden box is that transmission of heat and flame are slowed down so that an explosion is far less likely to harm you, your family, or the public servants trying to stop your house from burning down.
If you must store larger amounts of primers, and you can't go the Sammi route, then please consider using a lock on a plastic container such as a 50 cal size "drybox" from Cabelas or such.... lock the thing, and put it in a locked shed thats not attached to your house? Sounds like the safest choice to me....
Just sayin'....
Da
