There is no such thing as GB2099. It is SB2099, and it was proposed by Sen Jack Reed (D-RI) on 2/24/00.
The tax in question would have been imposed upon the manufacturer, not the owner. There was never an annual federal income tax clause contained in this legislation.
It did require that handguns be registered with the Feds, but not hunting rifles or shotguns. It required a Federal permit to own a machine gun, saw-off rifle or shot gun, and silencers.
Besides being an obvious violation of the 2nd Amendment, it also placed an onerous paperwork burden on local/federal law enforcement agencies, so it was never passed. In fact, it died without ever getting even a subcommittee hearing. However, it has been kept alive as an urban legend or bogeyman story by those who wish to co-opt this failed legislation for their own political objectives.
Arm yourselves with knowledge. It took me 10 minutes to research this bit of fiction and determine that SB2099 (SB stands for Senate Bill) was indeed proposed, but calmer heads prevailed and killed it - very early in its life cycle. So why, then, is it now being tied into the healthcare reform debate/fiasco? If you want to see how the sausage is made, then follow the money trail and ask who profits by bringing SB2099 back to life - even if it is only to use as a bogeyman on healthcare legislation.
If you fear losing your 2nd Amendment rights from the loopy left, maybe you should have as much fear from the loopy right who promote such falsehoods to support their opposition to whatever it is they are opposing. Be it the right or left, if they are successful at using a lie or a false fear tactic on one issue, they will do it again and again on any other issues that they see fit. We get the shaft, but their masters give them the gold for selling us out.