What I have done for mine is to purchase a normal leather holster (I bought mine from Cabelas) and cut a groove of about 1/2" wide starting from the top, where the rear sight of your pistol will rest, all the wa down to the lenght of the scope base mount. I use the Ruger scope base which is thiner than the Wiever style they are selling the pistols now. This makes the with of the cut narrower. When you are carrying the pistol with the scope, the pistol will be in the holster and the scope will show riding in the front of the holster.
Camba