The Reagan administration has delayed the release of a sensitive study expected to hold bad news for silver mining interests, and the result is a mini-boom in the metal's shaky price.

Producers of the precious metal were bracing nervously for July 1, when the administration was to announce after months of study whether it plans to sell 140 million ounces of silver in defense stockpiles--a move that could flood the market with silver and drastically lower its price.

But July 1 came and passed and no report emerged. Government officials attributed the delay to the complexity of the issue, but spokesmen for silver users who profit from low prices charged that politics was behind it.

Critics such as Walter Frankland, whose Silver Users Association includes photographic, electronic, welding and silverware companies, point out that western silver producers number among their powerful supporters Sen. James A. McClure (R-Idaho), chairman of the Senate Energy and Natural Resources Committee, Sen. Paul Laxalt (R-Nev.) and others with close White House ties.

The government has studied the silver stockpile question three times and each time recommended selling off the silver, so the industry had little hope that the hefty supplies would be kept off the market. "It would've been depressing for prices, no question about it," one Wall Street silver specialist said.

This time, Interior Secretary James G. Watt announced that the study assigned to his Cabinet Council on Natural Resources was running behind schedule and that any federal silver sales would be postponed indefinitely as a result.

No news turned into good news for the nation's troubled silver mines. Silver prices leapt, jumping 46.9 cents an ounce in one day on the New York Commodities Exchange after Watt's June 29 announcement. Prices climbed further last week, and market analysts gave the delay in the report part of the credit.

Watt did not explain the delay, and his aides assigned to the study did not return telephone queries last week.

It now appears that the report will emerge too late for Congress to act on stockpile sales this year. "It's not urgent," one high administration official said. And for once, some of President Reagan's strongest supporters say they are not complaining that the wheels of the federal bureaucracy grind slowly.

This is only the latest phase of a volatile debate, stretching across four administrations, over what the government should do with 139.5 million ounces of silver bars stacked in facilities at West Point and San Francisco. But it has drawn new interest because of the Reagan administration's stated goal of stimulating the troubled mining industry and the active involvement of key politicians from western mining states.

On the books, there is every reason to sell the silver in the national defense stockpile, the bank of minerals to be used in case of a war emergency.

The Federal Emergency Management Agency, which determines stockpile needs, said in three successive studies--in 1976, 1978 and 1980--that silver need not be stockpiled. Domestic supplies and imports from friendly countries could satisfy the nation's needs in a conventional war, FEMA concluded.

The Reagan administration, like others before it, set out last year to sell much of the excess silver, forecasting more than $1 billion in revenues from the sales over three years.

But the trouble began when the government announced details of its sales plans last fall. Silver prices dropped in one day from $10.96 to $9.72 an ounce on the New York Commodities Exchange. The government held six weekly auctions, but rejected all bids in the fifth and sixth weeks as too low. Only 2 million of the 10 million ounces offered by the government were sold.

Silver mining executives protested that the sales were aggravating their industry's already serious problems, induced by the national recession and the general slump in mining activity. They blamed the sales for the closing last year of some of the largest mines in Idaho, the nation's No. 1 silver-producing state.

Responding to the outcry, McClure sponsored an amendment to the 1982 Defense Appropriations Act, halting further sales until the administration again assessed silver stockpile needs in a study to be completed by July 1.

If the silver was again judged unnecessary, the study was to examine alternate ways of selling it--for example, by minting commemorative coins whose sale would not likely affect silver prices on commodities markets. Any disposal plan would require congressional approval, the amendment said.

The Cabinet council assigned FEMA the task of studying stockpile needs and the agency submitted its report a month ago, according to FEMA official Paul Kruger. He declined to reveal its contents, but another administration official close to stockpile issues said FEMA is not likely to reverse the stance of its last three reports.

"If you've come up with the same conclusion for three or four years, the possibility of coming up with the same answer is very, very high," the official said.

The remaining question is how to dispose of the silver. That part of the study, handled within the Cabinet council, remains unfinished, officials said. And as it is completed, supporters of the mining industry are lobbying heavily against further public auctions. McClure and Sen. Steve Symms (R-Idaho) introduced a bill that would use the stockpiled silver to mint a $10 commemorative coin, and have urged Reagan to support them.

"This is the worst possible time for the industry to see that material put on the market," said William Griffith, president and chief executive officer of Idaho's Hecla Mining Co., which mined 5.7 million ounces of silver last year. "So the producers are solidly behind McClure and Symms' push to have it coined."

But Frankland's silver users group insists that the coins would be expensive to produce and probably would sell poorly. "We don't want that silver to go into dresser drawers and not come on the market," Frankland said. "We certainly appreciate the problem the producers have in this economy, but there are 200 million consumers for whom the supply is a very big issue."

Many officials also question how much the stockpile auctions had to do with silver's price slide, which continued for several months after the sales were halted. The price bottomed out on June 21 at $4.885 an ounce--the lowest since the silver market collapsed after the buying spree by the Dallas-based Hunt brothers. It closed at $6.385 an ounce on Friday.

Some traders say the price might have rallied even without Watt's announcement simply because it had fallen so far. They contend that the initial jump in the days after the announcement was superficial, a response by "unsophisticated" buyers, and that last week's rally had more to do with general economic conditions.

But even skeptics concede that the mere existence of a large silver stockpile that the government officially doesn't need looms large over silver prices. The stockpile contains more silver than the total amount purchased in the United States last year, and industry officials say they are resigned that it will be sold some day. And when it is--even as coins--they predict the news will be bad for prices.

"All of us in the business of producing silver would rather see the silver stockpile disappear, assuming it isn't truly needed," said Hecla's Griffith. "But most of us would not like to see it done now."