That butt stock sleeve or cover is certainly different. I'd be interested in seeing just how it was done. It appears to have a wood grained surface, and may be somehow vacuum molded over whatever is hidden underneath the cover. It's almost like a Piñata that begs to be broken into to see what is inside. I just don't understand why whoever did it made it look like a Chinese SKS buttstock, when it would be just as easy to go for the more attractive Crossman Pellet gun look. One part of me thinks the original wood may be hiding underneath, and it was made to add a higher comb because it had too much drop. On the other hand, that bulbous grip makes me think there could be something really ugly underneath, like Bondo or even a crude piece of 2" x 6" lumber. I'm guessing it isn't AAAA Exhibition grade French Walnut.
I think it could still be a good candidate for a properly done Butt Transplant for someone capable of doing the work as a home gunsmith project. I'd be too curious to just leave it as is.