Its normal. I have a full bent Rossi that is drilled exactly the same way. The technique makes a little well at the end of the mortise which collects moisture. Also as another poster stated, that's the way it had to be drilled to meet the bottom of the chamber correctly. Looking at the pictures...
Sometimes the new flints are too coarse and there is too much friction to turn the wheel. When this happens to me, I roll the wheel on something very grippy, like a flat rug, and force the wheel to turn, smoothing out the top of the flint.
We got a tornado two years ago up here in North east Pa which is unusual. Tore up alot of trees and quite a few houses and buildings. The sky literally was green before it started. I never saw the sky look like that before.
So its you damn southerners weather responsible for all this rain I'm getting today. I may even get snow tonight. Stupid cosmic and his southern voodoo weather conjuring. Chasing is probably in on it too, praying to the sephilapods.
Good explanation olkofri. I wonder if there is a wood shaving still attached from the drilling process that gets pushed into the draught hole when the stem gets inserted, causing a block?