The U.S. Postal Service appears to be having some second thoughts about its reliance upon the Bureau of Engraving and Printing as the principal source of postage stamps. The reservations surfaced last month when the USPS' Office of Contracts issued a call for research proposals from firms interested in evaluating "alternative arrangements for [stamp] production."

According to an announcement which appeared in the Dec. 10 edition of Commerce Business Daily, the study is to include an examination of competitive bidding methods used by private-sector and foreign printing firms, as well as an evaluation of the present function of the BEP in the event that alternative methods of procuring stamps don't prove too appealing.

The factors to be evaluated include the cost of producing the stamps, quality, level of service, esthetics, timeliness of delivery, responsiveness to change, security and "philatelic integrity."

Under terms of the solicitation, researchers interested in taking a shot at the proposal were to have requested copies of the study guidelines in writing on or before Dec. 20.

Firms competing to do the study will be notified of the USPS's selection of the winning bidder early this year.

The firm which comes away with the research contract will have 75 days to deliver its draft report, with a formal presentation of the draft due three days later. The firm's final report is due 103 days after the contract is awarded.

While the Postal Service flatly denies that it's in any way dissatisfied with the quality of the products and services it receives from the Bureau of Engraving and Printing, it is concerned that the present arrangement is like "putting all your eggs in one basket."

If something were to affect the BEP's ability to produce a required quantity of stamps in a timely fashion, note postal officials, the nation's mail service might have a tough time meeting demand for stamps.

To guard against that, the Postal Service is hoping that the proposed study will come up with some innovative and economical alternatives for obtaining stamps.

According to one USPS official, the idea of commissioning the study had been under consideration for several months before the announcement was placed in Commerce Business Daily.

Collectors wishing to do a little duck stamp design competition judging on their own now have that opportunity.The U.S. Department of Interior's museum, located in the main Interior Department building (18th and C Streets NW), is highlighting a special display of approximately two dozen photographic reproductions of the top designs submitted for judging in this year's Migratory Bird Hunting and Conservation stamp design contest.

The handful of selected designs represent the top 20 finalists plus the first, second and third place winners selected this year by a panel of five prominent judges.

The exhibit, which runs through Jan. 22, enables collectors in the nation's capital to compare their choices for top honors with those of the judges.

This year's panel of judges sifted through a record 2,099 entries to determine which design would appear on Uncle Sam's 1982-1983 duck stamp.

Judging this year's entries were Richard E. McCabe, publications director of the Wildlife Management Institute; Tom Opre, chairman of the board of the Outdoor Writers Association of America; Edward L. Kozicky, director of conservation for the Winchester Group of the Olin Corp.; Herbert Doig, assistant commissioner for natural resources, New York State Department of Environmental Conservation; and Howard Pollock, first vice president of the National Rifle Association.

How well will your choices stack up against those of the judging panel? Find out by visiting the Interior Department's museum this week. Museum hours are 8 a.m. to 4 p.m. COINS

Commemorative coin collectors are sure to find this 'tis the season to be jolly. Last month Congress approved legislation calling for production of a special 90-percent silver half-dollar coin in honor of the 250th anniversary of George Washington's birth, an event to be celebrated this year. President Reagan is expected to sign the measure into law shortly after the holidays.

The legislation authorizes the U.S. mint to strike up to 10 million of the part-silver tributes in a size and composition matching that of the last commemorative half-dollar coin issued in 1954 in honor of Booker T. Washington and George Washington Carver.

Beside setting limits on how many of the coins can be minted, the legislation sets a deadline for striking the 50-cent pieces. Under terms of the authorization, all of the Washington half-dollars must be minted before Dec. 31, 1983.

Also spelled out in the legislation are some design requirements. According to the bill, both the obverse and reverse must bear designs emblermatic of the 250th anniversary celebration of Washington's birth. The measure also requires that the coin's design must feature a notation of its stated value and date of issue, as well as the inscriptions "Liberty, In God We Trust, United States of America, and E Pluribus Unum."

At the present time, the mint's chief engraver, Elizabeth Jones, is preparing several design approaches. These, it is hoped, will be ready for presentation to the nation's Fine Arts Commission at its January meeting. The commission's seven members will recommend which of the designs the secretary of the treasury and the director of the mint should elect to use, but their decision is in no way binding. The treasury secretary will have the final say.

According to a spokesman for the mint, production of the coin may take place in mid to late spring.

While the coin act doesn't dictate how the coins are to be sold -- that's left to the discretion of the treasury secretary -- it does set some guidelines on how much they'll cost. The price is to be equal to the cost of minting and distributing the coins, plus a premium of no more than 20 percent of the overall costs associated with creating and selling the coins.

The 20 percent surcharge represents sheer profit and will be deposited in the nation's general fund to help offset the national debt.