I spent so much time on this butt plate that I could have built a whole gun in the same amount of time. Being my second gun, I thought the wood had to be a mirror image of the inside of the butt plate, a big time consuming mistake.
Anyway, I worked and worked and couldn't get the bottom of the butt plate to match up with the wood, I always had about a .030 gap. I finally gave up, heated the bottom tip of the butt plate to cherry red and smacked it with a blacksmithing hammer, problem solved.
I believe they had cast this butt plate from melted ball bearings, a file would hardly touch it so there was no casual peening to close the gaps.