There is only one chance to get iconic Gris-Gris revolver during a particular gig (Treating Symptoms). You are required to get an access token (Slider's hideout storage room key).
Should you miss this key, there is no possible way to get this particular weapon, since for some reason Treating Symptoms gig area is walled off after the quest (some doors are locked with unpowered status, some previously open doors are now locked, some previously open passage way are now locked off with metal sheets, even the drainage entrance is locked with a fence).
I kindly suggest patching in an ability to get this weapon (as other 2 permanently missable weapons) since it is completely pointells and unreasonable to wall off content in the endgame, especially since this weapon doesn't require you to make any specific choices during the storyline as is the case with some other weapons.
As a remedy i suggest either:
A) Making the Treating Symptoms gig area open and explorable again to allow those of us who missed the key to pick it up after the gig;
B) Allowing Gris-Gris to be sold at a Black Market Vendor if it wasn't picked up after The Damned mission;
C) Creating a duplicate of Slider's hideout storage room key and placing it in open world or in some other mission (like the Damned) to allow access to the stash should the first key be missed during Treating Symptoms.
Should you miss this key, there is no possible way to get this particular weapon, since for some reason Treating Symptoms gig area is walled off after the quest (some doors are locked with unpowered status, some previously open doors are now locked, some previously open passage way are now locked off with metal sheets, even the drainage entrance is locked with a fence).
I kindly suggest patching in an ability to get this weapon (as other 2 permanently missable weapons) since it is completely pointells and unreasonable to wall off content in the endgame, especially since this weapon doesn't require you to make any specific choices during the storyline as is the case with some other weapons.
As a remedy i suggest either:
A) Making the Treating Symptoms gig area open and explorable again to allow those of us who missed the key to pick it up after the gig;
B) Allowing Gris-Gris to be sold at a Black Market Vendor if it wasn't picked up after The Damned mission;
C) Creating a duplicate of Slider's hideout storage room key and placing it in open world or in some other mission (like the Damned) to allow access to the stash should the first key be missed during Treating Symptoms.