Excellent first post buddy. Much better than mine.
As for the stock. I would have added a small semisphere of epoxy putty where the ridges were, sanded, so that the stock still locks into place but can be removed. Then you could sand the male stock end down so it slides smoother.
Kinda like this:
See those semi-spheres at the bottom that snap it into place?
Or, even attach the plunger cover from a Recon or Raider to the back, and attach the female end from a Raider/Recon stock to the Longstrike stock! I'm gonna do that if I get it.
Great mod as is though. As long as it stays in without a locking mechanism, you're golden.
Actually the way I did it the stock really sticks in there still. I have to pull it out with a great deal of force. But at least I can pull it out at all. I like the sound of your idea But I was just looking for a quick fix.