Why do you want to unload it?
Unloading the muzzleloader at the end of the hunt is a habit of modern-day hunters.
No way the frontiersmen did this.
They had to keep their rifles loaded constantly. Their lives depended on it.
They couldn't afford to waste all the powder and lead that a daily discharge would use up.
Also, if they were in Indian territory, a discharge would alert their enemies.
I have kept a TC Hawken, loaded with black powder, loaded for 8 weeks in humid central Georgia.
When the big moment came, the gun fired flawlessly, dead deer.
I have kept my Savage loaded for a year, and it has fired flawlessly.