Just about any good furniture wax will do the job well.
If you want something that's easily reapplied, use KIWI WAX TYPE SHOE POLISH. It has a Lanolin base and soaks into the wood nice and even.
Like all wax, it will wear off, but it's very easy to touch up when needed.
I like to warm it up first before applying it to a room-temperature stock.
Works well on the metal bits too.
You don't want to apply wax, oil or anything similar UNDER THE STOCK LINE, where the metal contacts the wood.
Dem-Bart makes a product called WAXYLENE Gunstock Wax.
It used to come in different colors.
It doesn't require warming and soaks into the wood quite well, giving it a deep luster.
I like it a lot.
The finish is usually smooth and dry to the touch when it's had the final coat and stands up quite well to wear and weather. It buffs up quite well.
Other than metal parts, does your rifle have a wood or composite stock? Both of the products mentioned can be applied to just about any type of stock if you follow the instructions.
I know a fellow that uses furniture wax on his composite stock because he likes the feel of the stock with it applied and hardened properly. His stock always looks new.