As momentum continues toward a new collective bargaining agreement between NFL owners and the league's players, general managers and agents are bracing for a frenetic free-agency signing period that could resemble the rush at a midnight opening of an electronics store when the latest high-tech gadget becomes available.

"It's going to be insane," said a prominent agent who has several high-level free-agent players.

Some team officials and agents continue to project that a deal will be consummated by mid-July and that teams will be able to sign, cut and trade players within a week of a deal being finalized.

The immediate frenzy to sign free agents could be like nothing we've seen because of the condensed period teams will have to shape their rosters before training camps are scheduled to open in late July or early August.

Though no terms have been finalized for free agency, team personnel and agents anticipate that players whose contracts have expired and have four years or more experience will become unrestricted free agents. That could mean close to 500 players will be available once a deal is struck, according to a player representative.

Raiders cornerback Nnamdi Asomugha, Packers defensive end Cullen Jenkins, Panthers running back DeAngelo Williams, Seahawks quarterback Matt Hasselbeck, Chargers running back Darren Sproles, wide receivers Sidney Rice, Santonio Holmes, Terrell Owens, Randy Moss and Braylon Edwards, 49ers defensive tackle Aubrayo Franklin and defensive ends Ray Edwards and Charles Johnson are among the high-profile free agents who could be on the open market.

There could be hundreds more restricted free agents, including those with "franchise tags," like Colts quarterback Peyton Manning and Chargers wide receiver Vincent Jackson.

Dozens of players currently on rosters also could join the ranks of desired free agents. Quarterbacks Donovan McNabb and Vince Young, wide receiver Chad Ochocinco, running back Marion Barber and offensive tackle Marc Colombo are among several veterans who could be released and out of work.

Another aspect that could add to the rabid pace of free agency is the number of teams who will dive head in, according to a team official and an agent. Typically, the majority of teams wait a few weeks for the initial wave of free agency to settle down and the expense of the first-wave of free agency to level off.

"They won't have time for that luxury," a league source said. "Those teams are going to be right there from the beginning just like everyone else."