A mini-replay of the recent battle over seniority and ideology on the House Armed Services Committee is shaping up over a challenge by conservative Rep. Beverly B. Byron (D-Md.) for the chairmanship of an Armed Services subcommittee.

The Democrats on the Armed Services Committee are scheduled to meet today in closed session to vote on subcommittee assignments and chairmen, and some committee members are predicting a "bloodletting."

Conservatives, still smarting over the replacement earlier this month of Rep. Melvin Price (D-Ill.) as chairman of the full committee by the more junior Rep. Les Aspin (D-Wis.), are lining up behind Byron.

The Maryland Democrat is challenging liberal Rep. Patricia Schroeder (D-Colo.) for the chairmanship of the subcommittee on military personnel and compensation.

Byron, who was first elected in 1978, says she decided to make the move after the Democratic Caucus ousted Price.

Aspin holds the top post on the personnel subcommittee, but he wants to create and chair a new subcommittee to develop a more coherent policy on defense issues, such as spending and arms control. Because members can only chair one subcommittee, he would have to relinquish his post on personnel. Schroeder is next in seniority.

Schroeder argued in a private meeting with committee Democrats on Monday that seniority entitled her to the chairmanship, according to some attending the meeting. But some conservatives said that Schroeder's plea left them cold since she was a key player in the move to put Aspin in charge of the full committee.

"Pat made a pitch that she has been here more than 12 years, and the seniority system says she should have the spot. It's the last argument she should have used," said Rep. Roy Dyson (D-Md.), who supports Byron and backed Price.

"Obviously those guys are saying: 'You live by the sword, you die by the sword,' " a Schroeder supporter said.

In order to avoid what he called a "civil war," Aspin suggested at the Monday meeting that he might drop the subcommittee proposal and instead create a panel to study policy issues. That would enable Aspin to keep the personnel subcommittee chairmanship.

But Aspin supporters say that he is reluctant to do that because such an ad hoc group would have far less clout in Congress than a subcommittee.

Sources said Aspin spent yesterday trying to work out a compromise to head off a major confrontation today. Aspin declined to comment, but supporters for both congresswomen said neither plans to back off and noted that both feel they have the votes to win.

Some representatives said that the Byron challenge indicates that the ripples from the Price ouster may be felt for some time, something most said would be disruptive.

"Some members have said that they're trying to make a point. Maybe that's true. But when does it end?" said Rep. Ronald V. Dellums (D-Calif.), one of the more liberal committee members, who says he is supporting Schroeder because of her seniority, not ideology.

"The institutional infighting . . . distracts from more important matters," Dellums said.