Project Appleseed

I found a looks-like-new Turner NM1907 sling at a gunshow for literally half price, but it's the light tan "natural" color that practically glows next to the for more subdued rifle on which it's mounted.  Is there an oil or leather care product that considerably (i.e. not just a little like most leather oils) darkens natural leather without affecting the feel and grip of the leather?

 Leather supply companies supply leather dye.
It it's not to oily you could roll it up and set in a strong cup of coffee.
Go to Lewiston ID and shoot early spring, the mud there darken it quite naturally.

I used neatsfoot oil on mine and it made it very dark and softened it too.  It matches my M1 nicely.

UL

Some of the dyes are alcohol based and may actually make the leather seem more stiff. Oil based dies can leave a slick sheen on the surface although a little mink oil is great for preserving and waterproofing. If you want a more natural texture, I would look for a cream. Find a western wear store and look for boot cream which you can get in brown or black. Use several coats working it into the leather until you get the desired color.

neatsfoot oil works well,  so does Hydrophane.

I have several 1907-style slings that look and feel great that are treated with these.

Thanks everybody for the suggestions.  The old-school coffee one is especially interesting - if I get drowsy while shooting and need a quick pick-me-up, I can just knaw on the leather for a bit.

Azmule,

I know a thing or two about leather because I make custom leather holsters  (www.malabargunleather.com).

We do make slings but don't have them advertised on our site.

The turner slings are top notch.  Personally, I would NOT use Neatsfoot oil on one unless I saw that it was drying out. Neatsfoot is a penetrant and can soften the leather and promote stretching. I've seen good quality slings that have been ruined by localized stretching.

If you want to darken it up, leave it out in the sun for a few days.

To preserve leather, I prefer Fiebing's Aussie Leather Conditioner.  It's a beeswax blend that seals but does not penetrate.

tk