What firearms that are imported from Russia is spelled out in the Code of Federal Regulations (CFR). Specifically 27 CFR 447.52. The .gov is required to publish regulations in the Federal Register. 27 CFR 447.52 is updated every April Fools day (no joke). I found the last one from 01 April 2005, and the list is the same, no Tigr. So I called the ATF Import Branch, and was informed by Erica Reid that it had been updated since April Fools day. She is supposed to fax me the new one.
Couple of years ago I spoke to a lawyer whom also imports firearms from Russia, who had a firearm placed on the orignial list back in 1996. He saw the new list in negotiations, and that it started with something like 125 firearms and was down to 100 or so, but said it did not contain any cool stuff like the SVT-40, SVD, or the Tigr mostly 22LR's and the like. So I lost interest, and this is the first time I have dug into the subject since then.
BTW, there is also a policy change (was not strictly prohibited by regulation) where by former US PROPERTY war implements (ie Garand, M1911A1, M1 Carbine) where to again be allowed to be imported. This is big news, but have not heard a peep about it other then the ATF letter indicating the change in policy.