Senator Williams was one of a number of Nationals MP to stage a late-night revolt in the Senate, crossing the floor to support lifting the ban on the rapid-fire seven-shot gun.

Fellow National Bridget McKenzie also crossed the floor, while four others, including three cabinet ministers, abstained from voting.

The motion to allow the importation of the firearm was voted down, but Nationals MP George Christensen described the act as warning shot, aimed at the government’s inaction on the issue.

Senator Williams said the Adler was a “tool of the trade” for farmers to control vermin, particularly wild pigs.

“I recall one incident on my own farm near Inverell where I had a double-barrel shotgun and five cartridges to try and kill a pack of wild pigs,” Senator Williams told The Leader.

“I managed to shoot one boar and two others, but the biggest fella got up and I had one shot left – thankfully he didn’t come after me or I would have been heading up the nearest tree.

“My point is with an Adler I could have controlled the situation, and farmers Australia-wide would be in the same boat.

“There is hysteria about the Adler but I think it is misplaced.”

Labor senator and the leader of the opposition in the Senate, Penny Wong, said the government was “now in tatters”, with MPs and ministers openly rebuking the position of Prime Minister Malcolm Turnbull.

However, Senator Williams dismissed suggestions of a division in the party ranks.

“The Nationals have the right to differentiate and sometimes we don’t agree on particular issues,” he said.

“It is laughable that Labor and the Greens claim this is proof of division in the Coalition. Sometimes even Labor and the Greens split on issues, but that is rare because individual members of their parties are told how to vote, not how they want to.”

Nationals leader Barnaby Joyce said he “absolutely” supported the right of his party members to vote independently, but declined to say what his position was on the firearm ban.

“The National Party is its own party,” Mr Joyce said.

“I’ve had discussions with both Wacka and Bridget but I respect their rights.”