Welcome to the forum, TNRat!
1973 is correct for the birth year. As to rarity, I have no idea.
Most 44's I've dealt with handle Magnums and Specials interchangeably, but some are more finicky than others. My stainless 44 likes them both, laps 'em up and spits 'em out just fine. My 357 Marlin will NOT feed shorter rounds, period.
Your accuracy sounds pretty typical, but a better test would be at 50 or 75 yards. Small variations won't show up at the closer ranges. As for the different points of impact with different loads, well, that's the nature of the beast. I can't explain why one load shoots to the left, when the others don't. Just another reason to find a load the gun shoots well, and adjust the sights to get it zeroed for that load.
As habits go, this one is a lot more fun than most.