Hi samualt:
I've been buying gun leather for more than 30 years. I'm a true holster junkie.
Years ago (late 60's-70's) custom leather generally meant hand tooled. Quality holsters were hand tooled (basket weave or floral patterns were the most common) and then the leather was moulded but not hand boned. Hand boning distorted the tooling and generally was avoided. Virtually all holsters were designed with some kind or retaining strap or thumb break.
Those holsters were commonly lined.
Beginning in the 1980's the trend in holsters were for open top designs. To secure the firearm, holsters were more commonly hand boned. Higher quality leather also became more common. (Hand tooling concealed many flaws, the cheaper leather offset the added hand work).
On a good quality hand-boned holster, a lining is unnecessary. The lining will wear more quickly than the holster. As a result a small amount of wobble is introduced that will cause wear faster than if the holster is unlined.
No matter what kind of holster you get, a blued gun will show some holster wear in time.
Also, horsehide holsters have become the rage today. Unless you plan on swimming with the holster, don't bother with the extra expense. The advantages of horsehide are (1) it's thinner than cowhide at the same weight, and (2) because it is far more dense, it will not absorb water like cowhide.
The disadvantage of horsehide are (1) you should never wear a horsehide holster without a gun in it. Horsehide creases easily and once creased, the holster becomes generally worthless. (2) It is more expensive than cowhide, and comes in fewer colors because it doesn't accept stain well. (3) Its overall wear will be the same as cowhide and last equally as long.
What you should do is to pick-up a can of Kel 110 Pure Silicone spray. Spray the holster both inside and out. It will reduce some of the friction, but it will also trap the natural oils in the holster, not discolor it (after it drys), and retard the holster's ability to absorb water. It will extend the life of your holster. The treatment should be repeated only once every three or so years.
