There are plenty of 6 inch versions of the H&R 999 Sportsman out there, but they are getting pretty pricey nowadays. But try finding a mint condition four inch version with original box. I found mine today.
The 4" barrel length is less common than the 6". This appears to be a very late gun, most likely bearing a serial number beginning with an "H". H&R's are easy to date, and there's a table for doing so in the following thread: The Harrington & Richardson Sportsman
Very nice. I had an opportunity to shoot a friend's H&R Sportsman years back, and it was great.
I'd also like to find a good one someday, but 2011's got me all sidetracked.
I have a pretty mint 6" Sportsman 999. Looks nice but wish I liked it more. Terrible DA, IMO. Rear sight doesn't secure properly for some reason. Accuracy is OK but nothing like a K-22 or Colt OM. Hard to believe they are worth so much.
Finally got one. Mine doesn't have the letter number so I believe it to be from the 1937 or 38. I only shoot shorts through it. Wish I would have started buying years ago. Kinda pricey but fun to shoot. Thanks