A bill to ease laws on the purchase of gun silencers is gaining momentum even as the US reels from the horror of one of the deadliest killings in its history, writes Bette Browne.

There have been more than 350 shootings this year, in which four or more people were wounded or killed in the US, according to the crowd-sourced website shootingtracker.com, which keeps a running tally of gun violence.

Braced for a fight, President Barack Obama last night unveiled the most sweeping proposals for curbing gun violence in two decades, pressing a reluctant Congress to pass universal background checks and bans on military-style assault weapons and high-capacity ammunition magazines like the ones used in the Newtown, Connecticut, school shooting.