I agree the front sight in the book's illustration is too big - it's more like a moon sight.
My aim is taken the same as the 'full sight' however the ball hits in the middle of the bead.
Thus, with my aging eyes, the bead is fuzzy, but the ball hits in the middle, so the sharp outside detail is not very important.
I still shoot these well and have won 8 or 9 monthly postal matches at ALR with that rifle over the last 2 years. It's my "target rifle"(14 bore).