Pardon my learning curve. I now have the size under control. I have more pictures if anyone wants them.

I believe the stock and butt plate are original. I poked around on the Internet and saw another Powell that had a similar butt plate. I don't understand the pistol grip on an English gun. I thought that was an American feature. And no checkering. So maybe it's a restock? The screw sticks out because I had the butt plate off. Just need to tighten down on it, that's all.