Don't know much...
The 999 was the final design for that pistol. It was preceded by the Sportsman, the Model 199 (SA only I believe) and an even earlier model whose name escapes me at the moment. There is a fella who used to run around the forums by the handle of "B. Goforth"---I believe his name was Brian Goforth. He likely knows more about these that anyone and put out a book here a few years back.
My Sportsman dates to 1938/39. It is cosmetically challenged but shoots just fine, thank you.
Complete thread:
- took a H&R 999 home this evening. I have wanted one - 
Rob Leahy, 
2013-05-09, 00:00 
- took a H&R 999 home this evening. I have wanted one - Fivegunner, 2013-05-09, 03:56
 - Cool! - Slow Hand, 2013-05-09, 04:02
 - Those H&Rs are getting right popular these days - 
FOG, 
2013-05-09, 06:45
- Slim Pickens on H&R revolvers - 
Bud, 
2013-05-09, 08:28
- I noticed some pretty high prices @ GunBroker recently - FOG, 2013-05-09, 08:37
 
 - Yes they are! I've wanted a 999 for a while... - 
Boge Quinn, 
2013-05-09, 09:03
- Here's a nice one - FOG, 2013-05-09, 09:44
 - Same here! I saw one here in TN for that too. - stonewalrus, 2013-05-09, 09:54
 
 
 - Slim Pickens on H&R revolvers - 
Bud, 
2013-05-09, 08:28
 - 999 history, please..... - 
Byron, 
2013-05-09, 08:58
- Don't know much... - Hoot, 2013-05-09, 11:01
 
 - me too! looked for reasonable priced one and finally - 
cable, 
2013-05-09, 09:39
- Thanks! I'd appreciate that. (nm) - Boge Quinn, 2013-05-09, 13:06
 
 - took a H&R 999 home this evening. I have wanted one - Drago, 2013-05-09, 11:22
 - took a H&R 999 home this evening. I have wanted one - SKgrips, 2013-05-11, 08:53