Question
Starter content written by the Rangium team to seed the community.
Keep powder in its original factory containers, period. The container is designed to burn (not explode) if there's a fire, and the label has critical info. Never consolidate into other jars.
Check your local fire code and homeowner's insurance for quantity limits. Many areas have thresholds where a wood cabinet (not a steel safe) is actually the recommended storage for powder.
Counterintuitive but important: a flammable powder is safest in a cabinet that lets it vent and burn, not a sealed magazine. Look up the established storage guidance for your area.
Store primers in their original packaging away from powder, and keep both cool and dry. Don't store them in a sealed steel box that could turn into a pressure vessel in a fire.
Keep an inventory and rotate. Powder and primers store for many years if kept cool and dry, but don't let humidity or heat cycles get to them. Good on you for thinking about this early.