In another round of the great wrestling match between Congress and the forces of television violence, legislators have come up with a new weapon. The Lock.

The latest draft of House communications subcommittee report on TV violence suggests that all new TV sets be outfitted with "locking devices" so that parents can prevent their children from changing the channel to a violent show.

All they'd have to do is to lock the set onto the station - presumably one with no violent shows scheduled, if such a station could be found - and the kids would be safe from cops , robbers, crime and punishment.

The report doesn't actually advocate that the locks be installed at once - just that the FCC look into this and other possible ways of regulating TV violence at the producing end. But the lock is the solution that committee chairman Lionel Van Deerlin (D - Calif.) likes best.

"I think that's the one thing that might have considerable appeal." Van Deerlin said yesterday after the report was made public. "You could lock the set on a particular channel and leave the room and know that when you come back the kid will not be watching, oh, something like "Soap."

"Soap" is the new fall comedy series from ABC that is reportedly light on violence but heavy on sex.

FCC Chairman Richard E, Wiley hadn't seen the report and wouldn't comment on it yesterday but a member of his staff, told of the lock idea, asked, "Are you putting me on?"

Told he was not being put on, the staff member said, "You MUST be putting me on."

Again assured of straight faces all around, he said, "I think my safest bet is no comment." I will be very interested to read the report, especially that (lock) recommendation."

Among the other recommendations: that an "unobstrusive Program rating service" be devised by networks and stations to notify parents when an adult program is about to start. One suggestion is that a small white dot be flashed in one corner of the screen, though the report concedes that kids might be attracted by the dot's promise of adult material and it would "accomplish just the opposite of its intended objective."

The report also asks the FCC to consider requiring stations to aim a specified percentage of their daily programming at children and to expedite an FCC petition filed by Westinghouse Broadcasting that would require networks to give their stations an opportunity to pre - screen upcoming network shows at least four weeks in advance of air dates.

And the report raises the possibility of "legislation designed to increase competition" in the production of TV programs, thereby lessening the grip that networks now have over their affiliated stations.

"The current three - network market structure of television bears primary responsibility for the high level of violence on television," the report states.

For all of that - including the looks he likes - Van Deerlin said he didn't think the report amounted to much.

"I doubt if it's going to be a very useful addition to the dialogue," he said. "It summarizes findings rather than raising new issues."

The subcommittee held four days of hearings to gather data for the report starting in July 1976 and concluding in March 1977. Van Deerlin hoped for quick approval of the report yesterday but a vote was delayed until next Tuesday because some members of the subcommittee hadn't read the report yet.

Rep. Lou Frey Jr. (R-Fla.) s* aid he hadn't even received a copy.

Some members of the subcommittee plan to offer amendments and minor changes. Rep. Henry A. Waxman (D - Calif.) has already submitted an "additional proposed conclusion" that takes the networksand the FCC to task for devising the "family viewing time" plan that a Los Angeles District Court later struck down as unconstitutional.

Waxman, whose constituency includes the production studies of Hollywood said at a meeting called yesterday to discuss the report. "I was so offended at the notion of network executives meeting behind closed doors with the FCC chairman" to dream up the family - hour scheme. He called it a "violation of the First Amendment."

The report states. "The way family viewing evolved made real to many in the program production industry the spectre of government - inspired censorship."

But he also said he thought it was "a terrific idea." He just didn't like the way it came to pass.