Among the nation's hyperactive special interest groups, from doctors to dairy farmers, none is as effective as the gun lobby in combining slick organization with membership zeal to create the perception of power on a single issue. For nearly 13 years, the N.R.A. and compatriot gun groups have successfully fought every attempt to strengthen the feeble Gun Control Act, passed after the assassinations of Robert Kennedy and Martin luther King Jr. Now, in the wake of the shooting of President Reagan, the lobby is ready to ward off another wave of proposed gun laws. Senator Edward Kennedy of Massachusetts and Congressman Peter Rodino of New Jersey last week introduced a bill that would ban the import, manufacture and sale of cheap, easily concealable handguns, known as "Saturday night specials," and require a three-week wait between the purchase and pickup of any handgun. Not only does the gun lobby have its cross hairs set to shoot that bill down; gun lobbyists even hope to pass a gun bill of their own that would riddle existing federal firearm regulations with as many holes as a road sign used for target practice.

The gun lobby believes that the right to bear arms is essential to individual freedom and safety and is absolutely guaranteed by the Second Amendment to the Constitution. This dedication produces a for-us-or-against-us bunker mentaiity that views compromise as heresy and provokes unremitting opposition to any politician whose support is less than total. Early in his career, former South Dakota Senator George McGovem favored banning small handguns, but in the face of N.R.A. pressure, he ended up supporting efforts to decontrol gun purchases. Nevertheless, the gun lobby last fall threw its support, and more than $30,000, behind his successful Pro-gun opponent, Republican James Abdnor. Says McGovern: "I think they're crazy, I really do. They think the most important issue in the country is to be able to walk around with a pair of six-shooters. Its maddening to reason with them."