[DonVoigt]

Also, when stretching the holster, to you apply the liquid used to both the "inside and outside" of the holster before placing the pistol in a heavy zip lock bag an inserting it into the holster ?

Depends on how much and where you need to stretch it!
Use the least amount possible.
If needed, insert the pistol as far as it will go(inside the bag) and see where the holster is too small.
Add water or IPA there; use a smooth stick or plastic handle to press and stretch the leather to the contour of the luger.

At least, that has always worked for me; I'm sure there are other "ways".