THE LEGISLATIVE tub-thumpers of the National Rifle Association have wasted no time zeroing in on Montgomery County's efforts to control indiscriminate bullet sales. In the process, they have blown the impact of this new law out of proportion. The measure is merely a sensible precaution in the name of public safety--a step that any law-abiding gun owner should welcome. In voting 5 to 2 for enactment of the bill, which was introduced by member David Scull, the county council has reflected a legitimate and growing concern about loose laws that encourage America's personal arms buildup.

All this law does is ban the sale of ammunition to people who cannot produce either a valid Maryland registration certificate for a gun or, in the case of out- of-state residents, proof that the gun was purchased legally. Translation: if you have a gun and say so, you can buy bullets to your heart's content, but if you have a gun and aren't willing to tell anybody, forget that ammunition because you make people nervous.

Sure, it's a backdoor local legislative attempt to control handguns, which by current law come under state regulation. But in cities and towns and counties all around the country, people who are sick and tired--and scared--of all the unregistered guns in the hands of unknown others around them are sending messages through their local governments to all levels of government to bring handguns and the ammunition that goes in them under control.

It is obvious that whatever Montgomery does to get a legal hold on guns and ammunition won't stop wielders of unregistered guns from crossing a county line for supplies. But if you're looking out for your life or for the lives of people in your family, you have got to start somewhere. Anybody else, gun owner or not, should be willing to abide by simple procedures to curb indiscriminate sale and possession of dangerous weapons.