Wall Street analysts expressed skepticism yesterday about whether an unusual tactic being used by Baltimore-based Fair Lanes Inc. to try to take over the bowling alley operations of Brunswick Corp. will eventually succeed.

Fair Lanes disclosed Monday it has bought 5.1 percent of Brunswick's stock and is considering buying more as a way of pressuring Brunswick to sell its 250 bowling centers to Fair Lanes.

Brunswick officials initially rejected but did not totally rule out the offer, and Wall Street analysts predicted it would not succeed.

"I wouldn't rate their chances very highly," said Paul Whelan, a vice president in the Pershing Division of Donaldson Lufkin Jenrette in New York. "I do not believe that Brunswick will acquiesce."

"I don't think it's going to work," said Stanley Fishman, an analyst with Fahnestock Co. in New York, discussing the move. "I don't think Brunswick will lie down on this."

Fishman described Fair Lanes' move: "This is the little pygmy trying to tear down the Brunswick elephant. It's kind of a creeping-up-from-behind tactic."

Fair Lanes, which had sales in fiscal 1981 of $53.1 million, is about one-twentieth the size of Brunswick Corp., whose sales were $1.1 billion.

Fair Lanes reported net income of $4 million on its 1981 sales. In addition to its 89 bowling centers, the company also owns half of Baltimore-based BTR Realty Inc. and operates a chain of 18 restaurants called The English Co.

Analysts said they doubt that Fair Lanes' unusual corporate gambit will succeed in part because of the financial strains the move may place on Fair Lanes.

Fair Lanes has so far spent $11.5 million for the 549,200 Brunswick shares it has already bought and has arranged lines of credit to purchase up to 10 percent.

But Fair Lanes is still digesting its recent takeover of Patterson, N.J.-based Treadway Cos., operator of 20 bowling centers and six motels. Fair Lanes has since sold five of the inns to reduce its debt.

The Treadway acquisition cost Fair Lanes about $12 million last year, Betty Schaefer, Fair Lanes representative, said yesterday. As of March 31, the company's total current liabilities were $13 million.

Brunswick earlier this year successfully fought off a takeover attempt by Whittaker Corp. of Los Angeles. To discourage Whittaker, Brunswick traded its Sherwood Medical Division to American Home Products for stock owned by American Home Products.

After the medical division -- described by analysts as the company's "gem" -- was sold, the takeover bid fizzled.

Fair Lanes' attempt to exchange Brunswick stock for the company's bowling centers in effect turns Brunswick's ploy against itself, analysts noted yesterday.

But because Brunswick has been through this type of corporate battle before, analysts give Brunswick management the edge in the duel with Fair Lanes.

The diversified Brunswick Corp., which also makes marine and technical products, has been considered undervalued by Wall Street analysts who say its parts are worth more, when added up division by division, than the company as a whole.

Fair Lanes Chairman Sidney Friedberg said Monday the company is considering the possibility of joining other investors in acquiring stock in Brunswick.

But analysts said the chances of Fair Lanes putting together a coalition to take over Brunswick were slim. "I don't think there's a whole line of people waiting to take over Brunswick, I don't think there's anybody waiting in the wings," said Harold Vogel, an analyst with Merrill Lynch Pierce Fenner & Smith in New York.

Analyst Fishman said even if Fair Lanes is unsuccessful in acquiring Brunswick's bowling centers, its investment in Brunswick stock could wind up being very profitable.

Fishman said Brunswick could offer to sell the shares back to Brunswick at a hefty profit. Citing a tactic employed by others in the past, he said Fair Lanes could tell Brunswick, "You want these shares back, fellas? Then pay me double for them."

Said Fair Lanes' Friedberg yesterday, "Some people think that we're nasty; others think we're feisty."