Now that I look at it, my version could do with some brightening up. But what I'm trying to say here is to add contrast and different hues to your choices of colour, and explore with different types of shading. I'm not sure what you were going with the random pixels all around the wood and all, I assume you were trying to get a wood texture. I'd say not to bother with that as you have only so much space. As with real guns, their stocks and base tend to have a more smoother look to them, and don't really focus much on the detailing. It's more of a pattern than a texture when it comes to real guns. Might I mention, if you're trying to make these for graal or any other type of work for graal, never ever use #000 white or black. When uploaded there're usually issues with transparency and such.

I'm not much of a gun person, but those are some tips I can give and guide you on.