Originally Posted by Birdwatcher
There was an incident in Texas years ago where a guy tending a campfire didn’t notice that the stopper on his powder horn had fallen out, powder dribbled out and the flask blew up on his hip.

You need a brass powder flask or a horn fitted with a mechanical cutoff.

https://www.trackofthewolf.com/Search.aspx/1?search=Flask


Don’t ever have an open can of powder anywhere near the bench when shooting. Don’t ever pour directly down the barrel from the flask, use a powder measure.

https://www.trackofthewolf.com/List/Item.aspx/85/1


Every Camp that I attended made shooters poor their powder into a powder measure plug the main container (Powder Horn) before pouring the powder into the barrel.

Birdwatcher has given you some real sound advice.