Police are becoming increasingly worried about the number of powerful, large-calibre air rifles being brought into the country.
The guns can be sold without a licence to people over 18 and at short range could easily kill a person.
The guns are marketed in the United States as "serious hunting guns" and are powered by compressed air and charged from a scuba tank. They fire a heavy .50 calibre lead slug at about 600 feet per second, and can be bought for as little as $70.
Some importers have already agreed to remove the big-bore guns from their shelves after approaches from police.
The guns can be imported by dealers with a licence and sold to people over 18 without a firearms licence. Police said the law was being tightened to make it harder to buy the guns but until the law was changed, police were asking dealers not to sell the big-bore guns.
"Dealers are actually voluntarily taking those off the shelves. They appreciate the risk with them," said Inspector Joe Green, police national manager of firearms licensing and vetting.
Police were also concerned about replica 9mm air pistols which fired a lead round which "looked exactly like" the projectile out of the 9mm semi-automatic pistols used by police. One 9mm replica seized by police was tested and fired a slug through two pieces of apple case timber.
Mr Green said the availability of replica air guns was a worrying trend.
"We would like to see some active controls."
The Mountain Safety Council's advisory committee on firearms safety recommended imported replica guns be treated as if they were real weapons.
In 1999 police shot dead a west Auckland man, Eddie Leo, when he pointed a fake Glock pistol at them near Kumeu. Several months later a teenager was arrested when he pointed a replica Glock pistol at member of the public outside a bank on Auckland's North Shore.
In 1997 a test asked police officers to pick a real gun from a line-up of replicas. Only three of 50 officers got the right gun.
The Arms Amendment Bill now before Parliament is likely to tighten control of some high-powered air guns, including high powered air rifles like the one alleged to have been used in the killing of undercover police sergeant Don Wilkinson in Auckland last month.
"The Amendment Bill No 3 has a section which would have classified that as a firearm which means you would have to have a licence to have it," Mr Green said.
NZPA