I use this:
https://www.sealsactiongear.com/cata...?idProduct=540
But the problem with having a holster that lets you fit the gun with the suppressor on mounted.............. you are about 1 pound of sideways pressure away from snapping the end of your barrel off. Best to use the gun as is for a sidearm, or focus on it as your primary when you mount the suppressor.
I have two of the Milspec holsters, they flop around way too much when walking, when running...............