Twenty years ago this Thursday, the federal government took a step that remains a call to arms for guns rights hardliners. Many Americans remember the Waco siege as a federal raid against the compound of the Branch Davidians, a religious sect whose leader, David Koresh, was physically and sexually abusing adults and children. But for pro-gun absolutists, the Waco siege was something else. The kind of government tyranny they expect more of during the second Obama administration, and the kind of repression they are already preparing to resist.

“#USA>> Do you want *NAZI #Democrats TELLING you What you can EAT or How many Bullets you can DEFEND YOUR CHILDREN WITH? #STANDandFIGHT #tcot,” tweeted @johnmatthew19 this week using the hashtag #StandandFight encouraged by the National Rifle Association, and the hashtag #tcot or TopConservativesonTwitter favored by the organizers of the Conservative Political Action Conference being held in Washington in two weeks.

At the same time that the gun lobby is helping to fuel threatening language on the Internet, it is trying to keep secret its financial backing for key witnesses testifying about gun violence before the Senate Judiciary Committee.

One witness, David Kopel, who testified on January 30, identified at the hearing as a law school adjunct professor, received more than $108,000 in grants from the NRA’s Civil Rights Defense Fund in 2011. Another witness, David T. Hardy, testifying Wednesday as a private attorney in Tucson, Arizona, received $67,500 in grants from the same NRA Civil Rights Defense Fund in 2011. Another witness testifying Wednesday, Nicholas Johnson, a Fordham Law School professor, spoke a year ago at an NRA Civil Rights Defense Fund scholars’ seminar.

NRA-backed or –affiliated scholars speak in measured tones, even as similar arguments are made more stridently by Second Amendment activists on the Internet.

These days Twitter gives them a new outlet while complementing older technologies. Back on February 28, 1993, shortwave radio hosts sounded an alarm. The U.S. bureau of Alcohol, Tobacco and Firearms, at the behest of Clinton administration Attorney General Janet Reno, was executing a search warrant on the Branch Davidians compound based on evidence—including witness testimony—that the sect had converted AR-15 semi-automatic rifles, the kind of weapon used in the Newtown massacre, into fully-automatic firearms in violation of federal law.

The Waco siege ended tragically with the deaths of 74 people, including 25 children, and today the Waco tragedy remains a gun rights cause célèbre. The government affidavit for the federal raid listed other weapons suspected of being at the compound including “flare launchers, over one hundred rifles, an M-76 grenade launcher, various kits, cardboard tubes, blackpowder and practice grenades,” noted legal scholar Kopel in the Hamline Journal of Public Law & Policy. He maintains the raid was unwarranted, as “to exercise one’s Second Amendment rights to the fullest degree is not against the law.”

The Senate Judiciary Committee identified Kopel in its witness list as an Adjunct Professor of Advanced Constitutional Law at Denver University Strum College of Law. In his written statement, Kopel also disclosed that he is an Associate Policy Analyst at the Washington, D.C.-based Cato Institute, and Research Director of the Denver-based Independence Institute.

But Kopel left out one thing: The gun lobby funds his gun rights research. The NRA’s Civil Right Defense Fund gave Kopel an Independent Institute Research Grant of $108,000 in 2011, and gave him and two other researchers another $55,000 the same year.

Yet, Kopel made no mention of any NRA funding before the Senate committee. Although he did mention the NRA, defending it in his written statement against one recent, retired liberal columnist’s suggestion to “declare the NRA a terrorist organization,” in addition to citing NRA literature a few times among his many footnotes.

Kopel also writes for the Of Arms and the Law blog run by Hardy, who is testifying Wednesday in the Senate Judiciary Committee. Hardy’s written statement only identifies him as a private attorney and makes no mention of the NRA. Hardy previously served the NRA as its Assistant General Council, according to a more complete bio at a California-based law firm where he Affiliate Counsel. The NRA’s Civil Rights Defense Fund gave Hardy four grants totaling $67,500 in 2011 to help fund his website, writings and research and even a short, educational film.

Kopel did not return calls requesting comment. Hardy said that his funding from the gun lobby never came up with Senate committee staffers. “They did not ask, I did not tell them,” he told msnbc after Wednesday’s hearing. “Most of it is for research and writing in law journals, some amicus briefs.” He added that NRA’s Civil Rights Defense Fund is giving him more financial support this year.

The first, nationally televised Senate hearings last month after America’s worst case of gun violence at the Newtown Sandy Hook Elementary School left 20 children and 7 adults dead, helped set a tone for the ongoing national debate. Yet, three out of the five main witnesses chosen by the committee’s Democratic chairman, Senator Patrick Leahy of Vermont, were staunch opponents of any form of gun control. Although former Congresswoman Gabrielle Giffords, who remains injured from a shooting in during a campaign event in her district, also spoke briefly and haltingly at the start of the hearing to make an emotional appeal for gun control.

A staffer for the Democratic majority side of the Senate Judiciary Committee told msnbc that Chairman Leahy wanted “a balanced witness panel.”

One witness on Jan. 30 was NRA chief executive officer Wayne LaPierre. Another was Gayle Trotter of the Independent Woman’s Forum, who was discredited by msnbc’s The Last Word host Lawrence O’Donnell, among others, for claiming that AR-15 long-range, semi-automatic rifles are effective for women to use at home to defend themselves and their children, when the only alleged example that she could point to was that of a woman using a shotgun instead. The third Senate witness in the first, televised hearing opposing gun control was Kopel, whose research few apparently knew was being backed by the gun lobby.

Kopel made no mention in his testimony or remarks of either the Waco tragedy or federal laws restricting fully-automatic weapons, even though he co-wrote a book, No More Wacos, and has penned several other pieces on the Waco siege.

“The simplest step to prevent a repetition of the Waco disaster would be to repeal the National Firearms Act of 1934,” wrote Kopel, referring to the law passed after Prohibition in response to violent gangsters like Al Capone that outlawed machine guns or fully-automatic firearms.

Since 1993, extreme gun rights rhetoric has become more mainstream.

“[W]e are now facing the single most devastating attack on the Second Amendment this country has ever seen,” said NRA Chief Executive Office Wayne LaPierre this month in Salt Lake City, Utah. For decades, LaPierre has tried to suggest that the NRA is really a mainstream American organization. But in the wake of what one NRA lobbyist called “the Newtown effect,” LaPierre has begun to sound like some of the same survivalists and other extremists still heard on shortwave radio and now read widely on the Internet.

“Hurricanes. Tornados. Riots. Terrorists. Gangs. Lone criminals. These are perils we are sure to face–not just maybe. It’s not paranoid to buy a gun. It’s survival,” penned LaPierre this month in The Daily Caller, using some of his strongest rhetoric to date.