Cult leader David Koresh avoided federal firearms restrictions by purchasing gun parts from dealers around the country and assembling the components into deadly, illegal automatic weapons.

Even though federal law bans gun sales across state lines, it doesn't stop dealers from selling replacement parts.And while the law bars conversion of semiautomatic weapons into machine guns, it doesn't prohibit the sale of parts used to make the changes.

Koresh took advantage of these features in the 1968 firearms statute to buy hundreds of gun parts, ammunition and explosives from dealers who shipped the items to his Waco, Texas, compound by United Parcel Service, according to affidavits by federal agents unsealed in court this week.

Bush administration officials discussed closing what a number of federal officials regarded as loopholes in the firearms law in a 1989 review of possible gun-control legislation. The idea was dropped.

But the tragedy at the Waco compound is providing fresh momentum to the drive for gun-control legislation on Capitol Hill.

Rep. Charles E. Schumer, D-N.Y., and Sen. Dennis DeConcini, D-Ariz., both said Congress should consider outlawing the interstate sale of gun parts and banning the sale of machine gun conversion kits.

Schumer held a news conference Thursday to call for stricter gun-control legislation, including a five-day waiting period for handgun purchases to give police time to prevent criminals from buying the weapons.