Sometimes I use vinegar/iron, or rotten horse chestnut stain (stinky as all get out, but good) liberally applied and dried. I've also had success with alcohol based leather dyes, Tandy or a similar brand. You can mix and blend these and they go in deep. Wear rubber gloves as it goes into skin well, too. This stuff seems to jump onto any clean garments that you are wearing, so keep your wife happy and wear your worn out clothes. You will at least need a bottle of dark brown, buckskin and red. Tung oil afterwards does a nice job.
Incidentally if you wish to replicate a U.S. Gov't arsenal military finish, use the dark brown and tung combo. If prepped correctly, the average person cannot differentiate it from the real thing. Letterkenny, Raritan and Ogden arsenals bought dark brown leather dye in 55 gallon barrels and dipped the stocks in an automated assembly line, air dried them on the hook, and dumped them in 10 ft. high piles for the armorers. Point being for Kentuckies, if you want a consistent finish, really slop it on and wipe any excess off about a minute later. You can age over these finishes and lighten "carry areas" and wear points as you wish.