Pentagon officials revealed yesterday that the armed forces will be enlarged by 500,000 men in the near future. The move will force local draft boards to "scrape the bottom of the manpower barrel." This increase will raise the total to 4 million from the present goal of 3,500,000.

The Air Force will be built up to a total of 140 groups and corresponding expansion of the Navy and Army is planned. A present pool of 600,000 potential 1-A's will probably be exhausted by July, 1952 Major General Lewis B. Hershey indicated recently.

July is the scheduled date for the release of some of the men inducted at the outbreak of the Korean war, who will then have served the two year term of duty the present draft law provides. To replace these, and to provide the additional men required for armed forced enlargement, tightening of the draft laws will be requested, Defense Department officials predict.

Men were then being drafted at the rate of 80,000 a month, and they will have to be replaced as they are released.

Senator Henry Cabot Lodge (R-Mass.) last week announced that as the result of a Joint Chiefs of Staff agreement, the Air Force woul dexpand from 95 to 140 groups, three more National Guard and one Marine Reserve division will be called to active duty, and the Navy will receive more ships.

The entire problem of the armed forces increase, the requirements for men to replace those who will soon be released, and the necessity for changing the draft laws and lessening the number of deferments was explained in an unpublished bulletin distributed throughout the Selective Services System's local boards.