Three persons were convicted yesterday of firearms, assault and burglary charges in connection with the takeover of a Georgetown boutique last November, but they were acquitted by a jury of more serious kidnapping charges.

Convicted by the jury after a week-long trial in U.S. District Judge Barrington Parker's courtroom were Leon Bullock, 23, of 2504 14th St. NE; Robert Johnson, 23, of 4335 Ponds St. NE, and Wayne E. Joyner, 22, of 6110 Breezewood Dr., Greenbelt.

They were found guilty of illegally possessing weapons, second-degree burglary, assault with intent to commit robbery while armed and assaulting a police officer whose belt was hit by a bullet during the siege.

Prosecutors and other court observers said they could not explain the accquittal on kidnaping counts that involved the holding of five persons at gunpoint for three hours in the Alonso Boutique Ltd. at 1610 Wisconsin Ave. NW.

Attorneys for the defendants argued generally that the three men had no intention of kidnaping anyone when they entered the boutique. The hostages escaped unharmed shortly before the defendants surrendered to police.

The takeover occurred Nov. 15 during an alleged robbery attempt at the men's clothing store. The capture of defendants ended afternoon of drama that brought scores of heavily armed, flak-jacketed police to one of George's main commercial areas.

The defendants, who have been jailed since their arrest, will be sentenced later.