BV and CC are reasonably easy to understand and use. OQ is harder for me and maybe if I was using this for a while I would be better able to evaluate the OQ. This appears to be a best gun but it is a hammer gun, it does have a Jones Underlever and it is 10g. I am not sure how you arrived at OQ5 based on reading the chart or maybe I just need more time and examples to study.
My gut told me on inspection of the pictures that is was an $800 gun. There appears to be a missing piece of wood in the butt stock and maybe some inlaid repair in the checkering. In person, things may be different but the bores were described as dirty, not bumpy.
