The big ammo dump at Cam Ranh Bay was a huge place where they simply cut back vegetation in a spot and dumped the stuff in the cleared spot. It then just sat out there in the rain and tropical heat. Monsoon flood or 110 degrees. No attempt to shelter it or anything. The only protection was the 3 foot long Monitor lizards hiding in the jungle. There was enough bombs, mortar rounds, artillery and small arms ammo there to fight for another couple of decades. In 66-67 we were shooting 105 rounds that were made in 1944, toward the end of my tour they had moved to Korean war wrapped steel cased 105. Point being, if they were using all that stuff after how it was abused and stored and it worked fine, if you are being prudent and check I don't think you need to worry too much about how your powder/ammo was stored. How many of these "Suggestions" are sent out by companies who make this stuff? I know that the only local gun shop won't accept any ammunition that is maybe 10 years old which is ridiculous. I saw a you tube video where a guy shot off some Martini-Henry (paper wrapped) 100+ year old ammo and it worked fine 3 out of 4, no hang fires, no apparent loss of power and only one dud.