The Adler A110, a lever-action manually-operated shotgun that can fire up to eight cartridges in as many seconds, has a temporary ban on its importation in Australia while the country decides whether it should have the same tough restrictions as pump-action shotguns and semi-automatic weapons.

The Adler model currently allowed in Australia fires up to five shots, under the least restrictive "category A" rules which make it relatively easy for recreational shooters to own less powerful guns, like low-calibre air-rifles.

But shooting enthusiasts have been showing on YouTube how easily these five-shot Adlers can be modified to hold up to 11 cartridges. The growing popularity of the easily-modified shotgun worries gun control advocates that Australia's world-standard gun control is slipping.

The future of the Adler shotgun is uncertain while politicians decide if it should face tougher restrictions. David Rowe

Concerns about the integrity of Australia's gun laws were exacerbated this week by NSW Liberal Democrat senator David Leyonjhelm, a shooting enthusiast. He claimed both the Abbott and Turnbull governments "dudded him" by promising to lifting the import ban in return for his vote on the Australian Building and Construction Commission legislation and overturning a Labor amendment on border protection.

Law enforcement agencies warned the Abbott government last July that up to 20,000 seven-round Adler shotguns were on their way to Australia, prompting then prime minister Tony Abbott to impose the initial 12-month ban.