Hopes more information about the Government's gun buyback scheme will shut down the rumour mill.

More details on the scheme are expected today at 10:30, with a press conference by Stuart Nash and Grant Robertson. 

It's after military style semi-automatic weapons, along with any parts that could convert a gun into one, were banned following the Christchurch terror attack.

Council of Licenced Firearms Owners spokesperson Nicole McKee says they want clear and concise detail - because there's been a lot of gossip since the scheme was announced.

"We've heard rumours that all parts, accessories and consumables will not be considered, and there could even be a restriction on the number of things that could be handed in."

She told Mike Hosking the final ban could go much farther than that.

"The new legislation is likely to now deem your grandfather's 22 weaver action as a prohibited firearm, so the effect is further reaching than just semis."

The buyback scheme's budgeted at $168 million - but some say it could be about three times that or around half a billion.

Lobbyists estimate a figure up to a billion dollars.