Shoot a box or 2 of black powder loaded ammo through it and clean it with Moose Milk (a homemade BP cleaner made with equal parts Rubbing Alcohol, Murphy's Oil soap and hydrogen peroxide).
Not even cigarette smoke can survive that! And you get to run off the mosquitoes on the range, too.
Seriously, nothing on the gun is porous enough to hold an odor. Give it a good bath in your favorite gun oil (pull the grips and hit the grip frame as well) and that should take care of any residue.
Student of the ancient Chinese art of Bang Pow.
Gun Shui adviser
"Civilized men are more discourteous than savages because they know they can be impolite without having their skulls split, as a general thing." Robert E. Howard, "The Tower of the Elephant" (1933)
Make 2020 the year of MABA- Make Alex Bartend Again.
I would start by just clean as normal after shooting. I don't think metal would smell. Unless gun is a lot of plastic.
It is rather unprofessional to have ruined your pistol case, and not replaced it.
"The strongest tactical move is always the one in which you reap the highest gain, at the lowest cost."