Federal and military personnel will probably get a 6.5 per cent pay raise in early October unless the economy takes an unexpected nose dive over the sumemr.

The increase would go to 325,000 white-collar cilivians here and nearly 100,000 active duty military personnel stationed in and around Washington. Worldwide, it would affect more than 3 million uniformed and white-collar federal aides and - if it stays at the 6.5 per cent level - would cost $3.2 billion.

The 6.5 per cent figure isn't solid yet, and the actual amount won't be determined until sometime in August or September. Experts say it is begining to appear that the 6.5 per cent amount - which was projected by both Presidents Ford and Carter in their budgets - will hold solid. They are certain Carter won't try to shave or delay the raises barring such an emergency as a serious economic backslide, an oil crises.

When the 6.5 per cent raise was projected in the Ford budget, and endorsed by Carter, many people incorrectly assumed the pay issue was settled. It doesn't work that way.

The budget estimates are merely projections. In past years, the actual amount of the federal-military pay increase has tended to be lower than the amount projected in the budget estimate of 6.5 per cent appears to be right on target.

Indicators are that the wage survey the Labor Department is making of private industry will conclude that goverment workers are due a raise of around 6.5 per cent to catch up with wage gains in the private sector.

Last year, the Ford administration cut back the amount through changes in the pay-comparison formula. That tiggered an AFL-CIO walkout from the advisory group that consults with "management" in government on the amount of the October pay raise.

After long and ticklish negotiations, the unions have returned to their advisory posts, with the assurances that they will be permitted to have real input into the pay discussions. Also, the Civil Service Commission and the Office of Management and Budget have agreed to add a third party - the Secretary of Labor - to the team of "pay agents" for the President.

The idea there is that the Secretary of Labor, more than any other Cabinet member, is sympathetic to workers, and that the unions will have a friend in court when pay matters are decided.

The unions also have been quietly assured that Carter - unlike Nixon and Ford - will not attempt to trim the amount of the raises. Carter retains the option of sending and alternative pay plan to Congress if the national economy is in trouble. Unions have been told that isn't likely and that the President would be reluctant to slap wage controls on federal workers unless private industry employees also are covered.

As always, however, don't spend the money until you get it. Don't budget for a 6.5 per cent raise (the amount could be slightly more, or less, or it could be staggered by grade). Indications are 6.5 per cent ballpark figure will hold through October and that would be the biggest federal-millitary pay raise in many years.

Xavier (Mike) Vela has been given the White House nod to be administrator of Labor's important wage and hour division. Vela, 39, was with the Agency for International Development and Office of Economic Opportunity.

National Federation of Federal Employes picked its insurance director, Tina Gray, as its employee of the year. She got a cash award with the honor.

Times Change: The U.S. Customs Service is now putting out travel tips for persons returning from vacations in Cuba, North Korea, Vietnam and Cambodia.

Barry Sussman, official pulse-taker for The Washington Post, will talk to the Washington Statistical Society at its June 2 dinner at the Washington Navy Yard. Sussman will discuss the pluses and minuses of polls in political campaigns. Reservations ($9 a ticket) from RObert O'Keef, 436 Sherrow Ave., Falls Church, 22046.