That's why I NEVER go to a gun show w/o my pocket copy of the RENE Guide. The devil is in the details.
Sounds as if it may have been a very good buy. At almost $200 difference in the asking price & current values,, if it was a BKH-36X with all the stuff & in minty condition, w/o a prefix in the serial number.
Having the RENE pocket guide can truly make a difference. I was at a show once,, saw a fairly nice OM Single-Six. It was a round gate, sporting a pair of aftermarket stags. I looked at it,, thinking; "I think that serial number is in the Flatgate range." Knowing a lot of guns had the loading gate replaced, I stepped away,, opened my book, found out I was correct, and went back to look more closely at the gun. It was pretty nice,, so I started discussing a "deal." I bought it.
THEN,, I said to the dealer; "I like these older ones,, so now I need to sell this NM Super Single-Six." I was carrying one but hadn't tried to do any swapping.
Turned out,, the dealer bought my NM for not a lot of difference in what I gave for the OM. I later sold the stags,, put on a correct set of grips,, added a flat loading gate, and after it was done,, I have less than $150 in a nice Flatgate!
Education & reference material can be worth more than the costs to get them.