It's not approved for shooting a corrosive powder with it.
It's only approved for shooting BH 209 powder. (Page 7)

Page 63 of the Maxim .50 Instruction Manual PDF details the cleaning procedure that should be done every 50 - 60 shots.
It's a simple 2 step warm water and then hot water rinsing process while the barrel is kept in an upright position with complete air drying required afterward.

I suppose that after cleaning, hot air can be used to facilitate the drying process

https://silencerco.com/wp-content/th...nual-small.pdf