It looks and works much like the now-banned military-style assault rifles and according to Jim Yates, chief executive from Guns NZ, who is among retailers selling the kits, that's the point.
"This is one of the few things that we can do to simulate the use of what we used to do with AR-15 rifles using your existing licence-permitted pistol ... and the pistol carbine kit."
However, the kits might have a shelf-life as Police Minister Stuart Nash said he had asked his officials for advice on them, and on accessories like extended magazines.
"What we have here is a type of weapon which I'm unaware of any pistol shooting discipline which requires the level of attachment - your red-dot sights and your 50-round mag - we need to make sure that our communities are safe and that people are using these weapons for legitimate purposes and are following the rules."
Nash said he had sought advice from police on whether these types of firearms were needed in New Zealand - though wouldn't say he thought they had slipped through the cracks in the latest round of law changes.
"I wouldn't say there's a loophole but what I would say is that as technology advances and gun dealers begin to push the envelope, we need to make sure that the Arms Act is fit for purpose."
To own a pistol people need a category B gun licence and getting that is a lengthy and difficult process.
By law, pistols can be fired only at a club which has endorsed the shooter, and shooters must compete in 12 events a year to keep their licence.
Nicole McKee from the Council of Licenced Firearm Owners says the stringent rules mean people using carbine kits are highly unlikely to pose a public danger.
"There are so many rules and regulations around pistol ownership somebody would have to be either a very good actor and totally committed if they wanted to do that."
Yates said he had sought advice from police and the Government on whether he was allowed to keep selling carbine kits.
He said he hadn't received a response so they remained on sale.
"Under the old existing law we can sell them because they're a part for a pistol - they're not a rifle, they're not a prohibited firearm or a prohibited firearms part because they are a part for a pistol and pistols are excluded from the amendment specifically."
Pistol New Zealand, the governing body for all pistol shooting clubs in the country, declined to be interviewed for this story but said in a statement they would not like to see further restrictions placed on pistols.
- RNZ
