FILE PHOTO: Firearms and accessories are displayed at Gun City gunshop in Christchurch, New Zealand, March 19, 2019. REUTERS/Jorge Silva/Files

FILE PHOTO: A view of Gun City gunshop in Christchurch, New Zealand, March 19, 2019. REUTERS/Jorge Silva/Files

Thirty-eight of the 59 Democratic candidates for the U.S. House of Representatives named to the party's "Red-to-Blue" program have made gun restrictions a top issue in their campaign platforms this year. embed code and instructions: https://reut.rs/2LDkShr

Democratic congressional candidate Aftab Pureval speaks at a campaign event in Ohio's first congressional district, in North Avondale, Ohio, U.S., June 13, 2018. Picture taken June 13, 2018. To match Insight USA-ELECTION/GUNCONTROL. REUTERS/Tim Reid

Democratic congressional candidate Aftab Pureval speaks at a campaign event in Ohio's first congressional district, in North Avondale, Ohio, U.S., June 13, 2018. Picture taken June 13, 2018. To match Insight USA-ELECTION/GUNCONTROL. REUTERS/Tim Reid

Gun safety advocate and former Democratic Congresswoman Gabby Giffords stands with Democratic congressional candidate Aftab Pureval at a campaign event in Ohio's first congressional district, in North Avondale, Ohio, U.S., June 13, 2018. Picture taken June 13, 2018. To match Insight USA-ELECTION/GUNCONTROL. REUTERS/Tim Reid

Democratic congressional candidate Aftab Pureval speaks at a campaign event in Ohio's first congressional district, in North Avondale, Ohio, U.S., June 13, 2018. Picture taken June 13, 2018. To match Insight USA-ELECTION/GUNCONTROL. REUTERS/Tim Reid

Gun safety advocate and former Democratic Congresswoman Gabby Giffords speaks at a campaign event for Democratic congressional candidate Aftab Pureval in Ohio's first congressional district, in North Avondale, Ohio, U.S., June 13, 2018. Picture taken June 13, 2018. To match Insight USA-ELECTION/GUNCONTROL. REUTERS/Tim Reid

Democratic congressional candidate Aftab Pureval speaks at a campaign event in Ohio's first congressional district, in North Avondale, Ohio, U.S., June 13, 2018. Picture taken June 13, 2018. To match Insight USA-ELECTION/GUNCONTROL. REUTERS/Tim Reid

Gun safety advocate and former Democratic Congresswoman Gabby Giffords speaks at a campaign event for Democratic congressional candidate Aftab Pureval in Ohio's first congressional district, in North Avondale, Ohio, U.S., June 13, 2018. Picture taken June 13, 2018. To match Insight USA-ELECTION/GUNCONTROL. REUTERS/Tim Reid

Canada's Public Safety Minister Ralph Goodale takes part in a news conference on Parliament Hill in Ottawa, Ontario, Canada March 20, 2018. REUTERS/Chris Wattie

Canada's Public Safety Minister Ralph Goodale arrives at a news conference with Health Minister Ginette Petitpas Taylor on Parliament Hill in Ottawa, Ontario, Canada March 20, 2018. REUTERS/Chris Wattie

Canada's Public Safety Minister Ralph Goodale speaks during a news conference on Parliament Hill in Ottawa, Ontario, Canada March 20, 2018. REUTERS/Chris Wattie

Canada's Public Safety Minister Ralph Goodale listens to a question during a news conference on Parliament Hill in Ottawa, Ontario, Canada March 20, 2018. REUTERS/Chris Wattie

U.S. Supreme Court is seen in Washington, U.S., November 27, 2017. The Court, which has avoided major gun cases for seven years, on Monday declined to hear a challenge backed by the National Rifle Association to Maryland's 2013 state ban on assault weapons enacted after a Connecticut school massacre. REUTERS/Yuri Gripas

U.S. Supreme Court is seen in Washington, U.S., November 27, 2017. The Court, which has avoided major gun cases for seven years, on Monday declined to hear a challenge backed by the National Rifle Association to Maryland's 2013 state ban on assault weapons enacted after a Connecticut school massacre. REUTERS/Yuri Gripas

U.S. Supreme Court is seen in Washington, U.S., November 27, 2017. The Court, which has avoided major gun cases for seven years, on Monday declined to hear a challenge backed by the National Rifle Association to Maryland's 2013 state ban on assault weapons enacted after a Connecticut school massacre. REUTERS/Yuri Gripas

U.S. Supreme Court is seen in Washington, U.S., November 27, 2017. The Court, which has avoided major gun cases for seven years, on Monday declined to hear a challenge backed by the National Rifle Association to Maryland's 2013 state ban on assault weapons enacted after a Connecticut school massacre. REUTERS/Yuri Gripas

U.S. Supreme Court is seen in Washington, U.S., November 27, 2017. The Court, which has avoided major gun cases for seven years, on Monday declined to hear a challenge backed by the National Rifle Association to Maryland's 2013 state ban on assault weapons enacted after a Connecticut school massacre. REUTERS/Yuri Gripas

U.S. Supreme Court is seen in Washington, U.S., November 27, 2017. The Court, which has avoided major gun cases for seven years, on Monday declined to hear a challenge backed by the National Rifle Association to Maryland's 2013 state ban on assault weapons enacted after a Connecticut school massacre. REUTERS/Yuri Gripas

U.S. Supreme Court is seen in Washington, U.S., November 27, 2017. The Court, which has avoided major gun cases for seven years, on Monday declined to hear a challenge backed by the National Rifle Association to Maryland's 2013 state ban on assault weapons enacted after a Connecticut school massacre. REUTERS/Yuri Gripas

Visitors stand in line outside the Supreme Court in Washington, U.S., November 27, 2017. The U.S. Supreme Court, which has avoided major gun cases for seven years, on Monday declined to hear a challenge backed by the National Rifle Association to Maryland's 2013 state ban on assault weapons enacted after a Connecticut school massacre. REUTERS/Yuri Gripas

(L-R) Senators Robert Casey (D-PA), Chris Murphy (D-CT) and Richard Blumenthal (D-CT) hold a news conference to demand Congress' immediate action to reduce gun violence, on Capitol Hill in Washington, U.S. October 3, 2017. REUTERS/Yuri Gripas

(L-R) Senators Robert Casey (D-PA), Chris Murphy (D-CT) and Richard Blumenthal (D-CT) hold a news conference to demand Congress' immediate action to reduce gun violence, on Capitol Hill in Washington, U.S. October 3, 2017. REUTERS/Yuri Gripas

Senators Chris Murphy (D-CT) (L) and Richard Blumenthal (D-CT) hold a news conference to demand Congress' immediate action to reduce gun violence, on Capitol Hill in Washington, U.S. October 3, 2017. REUTERS/Yuri Gripas

(R-L) Senators Robert Casey (D-PA), Chris Murphy (D-CT) and Richard Blumenthal (D-CT) arrive at a news conference to demand Congress' immediate action to reduce gun violence, on Capitol Hill in Washington, U.S. October 3, 2017. REUTERS/Yuri Gripas

(R-L) Senators Robert Casey (D-PA), Chris Murphy (D-CT) and Richard Blumenthal (D-CT) arrive at a news conference to demand Congress' immediate action to reduce gun violence, on Capitol Hill in Washington, U.S. October 3, 2017. REUTERS/Yuri Gripas

Senators Chris Murphy (D-CT) and Richard Blumenthal (D-CT) (R) hold a news conference to demand Congress' immediate action to reduce gun violence, on Capitol Hill in Washington, U.S. October 3, 2017. REUTERS/Yuri Gripas

Senators Chris Murphy (D-CT) and Richard Blumenthal (D-CT) (R) hold a news conference to demand Congress' immediate action to reduce gun violence, on Capitol Hill in Washington, U.S October 3, 2017. REUTERS/Yuri Gripas

Senator Chris Murphy (D-CT) speaks during a news conference to demand the Congress' immediate action to reduce gun violence on Capitol Hill in Washington, U.S., October 3, 2017. REUTERS/Yuri Gripas

Senator Chris Murphy (D-CT) speaks during a news conference to demand the Congress' immediate action to reduce gun violence on Capitol Hill in Washington, U.S., October 3, 2017. REUTERS/Yuri Gripas

Senator Richard Durbin (D-IL) speaks during a news conference to demand Congress' immediate action to reduce gun violence, on Capitol Hill in Washington, U.S. October 3, 2017. REUTERS/Yuri Gripas

U.S. Senator Pat Toomey (R-PA) speaks to the 38th annual Conservative Political Action Conference meeting in Washington DC, U.S. February 10, 2011. REUTERS/Larry Downing/File Photo

A sign along the Massachusetts Turnpike in Boston May 20, 2014. The iconic sign bearing pro-gun-control messages has hung near Boston's Fenway Park for almost two decades is going to lose its home in March 2015. Massachusetts features a counter tracking the more than 45,000 people killed by guns in the United States since the December 2012 attack on a Newtown, Connecticut, elementary school. REUTERS/Brian Snyder (UNITED STATES - Tags: CRIME LAW)

A sign along the Massachusetts Turnpike in Boston May 20, 2014. The iconic sign bearing pro-gun-control messages has hung near Boston's Fenway Park for almost two decades is going to lose its home in March 2015. Massachusetts features a counter tracking the more than 45,000 people killed by guns in the United States since the December 2012 attack on a Newtown, Connecticut, elementary school. REUTERS/Brian Snyder (UNITED STATES - Tags: CRIME LAW)

A sign along the Massachusetts Turnpike in Boston May 20, 2014. The iconic sign bearing pro-gun-control messages has hung near Boston's Fenway Park for almost two decades is going to lose its home in March 2015. Massachusetts features a counter tracking the more than 45,000 people killed by guns in the United States since the December 2012 attack on a Newtown, Connecticut, elementary school. REUTERS/Brian Snyder (UNITED STATES - Tags: CRIME LAW)

A sign along the Massachusetts Turnpike in Boston May 20, 2014. The iconic sign bearing pro-gun-control messages has hung near Boston's Fenway Park for almost two decades is going to lose its home in March 2015. Massachusetts features a counter tracking the more than 45,000 people killed by guns in the United States since the December 2012 attack on a Newtown, Connecticut, elementary school. REUTERS/Brian Snyder (UNITED STATES - Tags: CRIME LAW)