I think the all plastic stocks are glued pretty good... and I don't have one in bad enough shape to sacrifice to find out... sorry.
Maybe try one of those that DJ mentioned. Probably a lot less heart ache if things don't go well due to the lower cost of the non-HK. The one I tried was a factory HK and after a rap with a heavy mallet didn't work, I resorted to putting the cap end in a vice and sideloading the stock until the cap snapped off in a "completely shot kind of way". Like Shattered said they are glued on quite well. I would try one of the POF from RTG or a US one first.I had some POF & USA made ones that the butt cap popped off fairly easy. A good rap on the bench & off it comes.
What are you thinking about using for restoration.. Like fast dry 2 part epoxy?Actually yes, it's going well so far. The butt cap isn't glued in it's just press fit. I used a dremel to cut through the plastic weld around the butt cap then I used a screw driver to carefully go around prying it off. I heard a pop and the butt cap was in my hand.