U.S. District Court Judge Oliver Gasch yesterday sentenced a formerGeneral Services Administration contractor to six months in jail after he admitted stealing $310,000 from the government agency.

It was the first jail term imposed by Gasch on a contractor convicted in the scandal involving corruption at GSA.

In addition to the six-month jail sentence, Gasch yesterday placed the covicted contractor, Robert C. Wear, of Fairway Hills, Md., on 2 1/2 years of probation.

Wear admitted receiving $370,000 in GSA contracts to repair and alter U.S. buildings in Washington and doing only $60,000 worth of the work. He then split the remaining $310,000 with GSA employes who wrote phony contracts covering the nonexistent work.

Assistant U.S. Attorney William S. Block told Gasch that about $100,000 of the money was retained by Wear.

Charles W. Halleck, Wear's lawyer, said Wear had cooperated in the GSA investigations. He said the Internal Revenue Service is now proceeding against him to recover taxes on the full $310,000, even though he kicked back most of it to GSA employes.

Block agreed Wear had cooperated but asked for a jail sentence to deter future GSA crimes.