CDNN cleared out a lot of the African models a few years back, as I recall, there were numerous non catalog iterations. Whether from Davidsons or Lipseys or one of the other numerous distributors, I couldn't say. This was just prior to the changeover to threaded barrels on the Alaskans, Africans and Guide Guns. I ended up with a LH African that I love for a bargain price.
If I'm not mistaken, as long as it can be assembled from stock parts, Ruger will do an exclusive run for a guaranteed order of just a few hundred (maybe 500?) units. This results in more dealer/distributor exclusives than you might see from other manufacturers.
Yours looks to me like a non stainless Alaskan in an African stock instead of the Hogue. As to who's special run, who knows...but it looks like a fun, handy rifle.
ETA: looking at your pic again, it may have been cerakoted. Most Rugers have a stainless bolt handle and extractor. I'm not well versed in all their models, and I'm sure I'll be corrected shortly, but I'm not aware of any 77 based rifles with a black bolt from the factory. But again, all bets are off when dealing with distributor exclusives.