Any plastic-type holster that is close can be easily adjusted with a good heat gun. Go at it carefully, heat it up, insert the gun, and continue to apply the heat. Withdraw the heat, and let it cool with the gun in the holster.
If you get to heavy handed with the heat gun, you'll ruin the holster, so go slow.
(Harbor Freight has the guns used to remove tiles, etc., for under $10.)