For the SA's, here's a brief overview:
BKH = old model Blackhawk
Following digits express caliber and barrel length
3 = .357 mag (flattop, 4-5/8" barrel)
34 = same as above but used after other barrel lengths and also non-FT OM's
36 = .357 mag, 6.5" barrel (FT and non)
30 = .357 mag, 10" barrel (FT only)
4 = .44 mag (flattop 6.5" barrel)
46 = same as above but used later after other lengths
47 = .44 mag FT with 7.5" barrel
40 = .44 mag FT with 10" barrel
31 = .30 Carb OM, 7.5"
41 = .41 Mag OM, 4-5/8"
42 = .41 Mag OM, 6.5"
44 = .45 Colt OM, 4-5/8
45 = .45 Colt OM, 7.5"
S47 = old model Super Blackhawk (.44, 7.5")
RSS = Single Six, 5.5"
RSS5 = same as above
RSS4 = Single Six, 4-5/8"
RSSM = Single Six Magnum (.22 WMR) 6.5"
RSS9 = Single Six, 9.5"
RSSE = Single Six, Engraved (5.5")
LWAC = Lightweight Single Six, Alloy cylinder (4-5/8")
LWSC = Same but with steel cylinder
SC = Super Single Six (4,5,6 for bbl length)
The NM's have similar numbering but it starts getting confusing fast as new calibers and barrel lengths came out. And stainless.
K = stainless
GK = glossy stainless
BN = NM Blackhawk
NR = NM Super Single Six
S = NM Super Single Six LR only
S47N = NM Super Blackhawk
etc, etc...