DoogMeister

have only used 91% isopropyl alcohol with good results.

I picked up a piece of leather similar to yours on a clearance from a big box arts and crafts store about a month ago, with some folding issues although not as severe as yours. I wet the leather on both sides, then rolled it around a large (maybe from a piece of carpet?) cardboard tube I had been using for something else. Took two or three iterations of this, but it finally went almost completely away. Hope that helps.

Have used Feibing's leather sheen applied with an airbrush (not the aerosol can product). I buy a 6oz? bottle from Hobby Lobby. No problems.

Got the Harbor Freight Deluxe airbrush. I use Feibing's pro dyes, almost always straight. Use91% Isopropyl alcohol for thinning and cleaning.

Made one for a single-shot rifle and used what Pastor Bob said. 8-9 oz for the wrap, and 5-6 oz for the cartridge loops. Used a piece of scrap 6-7 oz for the buttplate cover. Worked out quite well. Used a piece of suede scrap to protect from the grommets. Will have to post pictures.