WASHINGTON — The House could pass legislation as early as this week that would roll back decades-old restrictions on gun silencers, opening up the market for a device that critics say would make it difficult in a mass shooting to detect where gunfire is coming from.

The House is also expected to move this fall on separate legislation that would allow people to carry their legally concealed weapons across state lines into jurisdictions, such as California, that tightly restrict weapons concealment.

The silencer measure is part of the Sportsmen Heritage and Recreational Enhancement Act, a broad-ranging gun bill delayed in June after House GOP Whip Steve Scalise, R-La., and two Capitol Hill police officers were wounded by a gunman who opened fire on a congressional baseball practice session.

Critics say silencers — called noise suppressors by supporters and heavily regulated by the federal government for more than eight decades — would make it harder for police officers to locate a shooter in an attack.

“What it does is it disperses the sound, so you can’t identify where the sound is coming from,” said Rep. Mike Thompson, a St. Helena Democrat and avid hunter who opposes the bill. “It puts both law enforcement and the public at risk.”

But Republicans say the provision, called the Hearing Protection Act, doesn’t really silence the sound of gunfire, only diminishes it enough to shield hunters and recreational shooters from hearing damage.

“It isn’t a silencer because it still makes sound, but what it does is cuts the percentage of the noise down to make shooting sports a little nicer for people’s hearing,” said Rep. Doug LaMalfa, R-Richvale (Butte County).

“There’s a lot of false narrative being driven by this,” he said. “Anything to do with making guns more available or more convenient for people is going to find opposition by the left.”

House Minority Leader Nancy Pelosi, D-San Francisco, said Republicans have the votes to pass both bills. Democrats can probably block them in the Senate with a filibuster, but the legislation shows the GOP in full pursuit of a pro-gun agenda despite a rise in mass shooting incidents, including one that struck their own.

On a broad basis, the 144-page bill seeks to loosen restrictions on hunting and shooting on public lands. It would, for example, reverse an Obama administration ban on lead tackle and ammunition from most federal lands; amend the Migratory Bird Treaty Act to allow shooting of birds over unharvested cropland; ease fishing restrictions in marine sanctuaries; remove Endangered Species Act protections for Great Lakes gray wolves; and ban the purchase of new wetland and bird habitat.

It would also legalize the sale of armor-piercing bullets so long as the manufacturer claims the ammunition is made for “sporting purposes.”

The legislation is a top priority for the National Rifle Association, while environmental groups and those pushing greater gun regulation are strongly opposed. A number of city police chiefs have signed a letter of opposition.

In their letter, the police chiefs said the main market for silencers now is “military tactical teams who use silencers to confuse the sound of gunfire and confound an enemy’s response to surprise attack.”

“The widespread and uncontrolled distribution of silencers to an unwary civilian population, combined with the sheer number of firearms freely available in America,” the letter said, “is a step in the wrong direction and will result in tragedy, including violence directed at police officers that will be difficult or impossible to investigate effectively.”

The second major weapons legislation the House is planning to consider separately this fall would allow people to carry concealed weapons in any state if it is allowed in the state where they live.

The bill would undermine regulations in states such as California and New York that require applicants for such a permit to demonstrate a need and submit to background checks. A dozen states have no permit requirement for carrying a concealed weapon.

Thompson, who has led a Democratic task force to reduce gun violence since the 2012 Sandy Hook elementary school shooting, said the bill “would allow people to carry their guns wherever they wanted to carry them.”

Republicans are advertising the bills “under a facade of, ‘It’s for hunters,’” Pelosi said. “Hunters need armor-piercing bullets? They need silencers? They need to conceal and carry to hunt?”

The House Natural Resources Committee approved the Sportsman Heritage and Recreational Enhancement Act, known as the Share Act, last month on a party-line vote, with four California Republicans — LaMalfa, Tom McClintock of Elk Grove (Sacramento County), Paul Cook of Yucca Valley (San Bernardino County) and Jeff Denham of Turlock (Stanislaus County) — joining the majority.

The National Rifle Association said versions of the bill have passed the House before, but that this one is “the most ambitious and consequential yet,” in part because of the silencer provision. A key backer is Donald Trump Jr., the president’s eldest son, who appeared in a video touting their use to increase hearing safety and also get “little kids into the game” because the devices reduce a gun’s recoil.

Critics argue that gun sales have slumped since Trump’s election, leading gunmakers to look for a new source of revenue, and they have found one in silencers.

“If you buy one, you’ve got to buy a gun to put it on, because the barrel’s got to be threaded,” Thompson said.

Silencers, like machine guns, have been strictly regulated since 1934 under the National Firearms Act, in response to mob killings. Current law requires buyers to submit fingerprints and a photograph, pay a special tax, submit to a background check and notify local law enforcement.

“No one who is willing to go through the process has a problem obtaining one,” said Peter Ambler, executive director of Americans for Responsible Solutions, a gun violence prevention organization founded by former Rep. Gabrielle Giffords, who was gravely wounded in a gun attack in 2011.

But because of the regulation, Ambler said, “you see remarkably few crimes committed with silencers or machine guns, compared to guns writ large, where our current laws are inadequate to deal with crimes being committed by them.”

Ambler’s group is putting pressure on seven California House Republicans representing districts that Hillary Clinton won last November, releasing polls showing that both bills are unpopular in their districts.

With concealed-carry reciprocity, “you’d have a situation where somebody could come from Arizona, where there is no permit required at all to carry a gun,” Ambler said, “and that person’s Arizona residency would override California law and allow anybody with an Arizona driver’s license or resident card to carry a loaded gun in the state.”

The bill’s author, Rep. Richard Hudson, R-N.C., has argued that gun owners would still have to obey the laws of the states they are visiting, even if those states have to recognize their right to carry guns.

A spokesman for House Majority Leader Kevin McCarthy, R-Bakersfield, would not say when either bill would come to the floor, but lobbyists on both sides said the Share Act vote is imminent. With committee passage, a House vote could come at any time.

Carolyn Lochhead is The San Francisco Chronicle’s Washington correspondent. Email: clochhead@sfchronicle.com Twitter: @carolynlochhead