The only chunk specific sight I ever saw, was a photo send to me by Mark H.- consisting of an adjustable rear sight- with a tall U notch. The front sight was a bead, that was held in the bottom of the U notch, using the notch as a topless peep sight. I can 'see' this sight working very well with very little practice needed to get used to it - if you are comfortable with aperture sights, that is.