[Unclenick]

Also, I will add it is not a good idea to put silica or any other desiccant in with ammo. Water vapor molecules are very small and, unlike liquid water, don't have surface tension to keep them out of tight spaces. Norma's 2013 print manual shows that conventionally loaded ammunition will have its powder equalize with the storage RH over a period of about a year, and powder burn rate gets ten to twelve percent faster when bone dry as compared to storage in 80 percent RH. So desiccating cartridges will raise pressure. It may not be to a dangerous degree, but if the load was already a maximum load, it could take you into sticky bolt lift territory, and it is enough to detune a match load.

The powder companies use somewhat different storage and packing humidities, so I would call your powder's distributor and ask what storage RH they use and confirm it is the same for powder they load for load testing. Try to keep your powder in that RH. I use 60% if I don't know. If you can copy the distributor's conditions, you will be working as close to their load data numbers as you can get.