Gun-owners are leaving satisfied from New Zealand's first Government buyback event.

Nearly 100 people have come through Christchurch's Riccarton Racecourse showroom since the buyback began at 10am.

Police say so far 35 firearms have been handed in, 24 of which have been processed.

They have also received 42 parts.

There are about 40 people still waiting inside.

One gun owner - who wants to remain anonymous - says he didn't have much faith going in.

"I was selling my hunting firearm - it's a semi automatic. I got $13,000 for it."

He says he's happy with that, as it was a very expensive purchase.

"I didn't think this would be a fair process at all - I wasn't particularly happy about it. But the outcome was good and they handled it well."

Another man, who handed in his SKS semi automatic, says the entire process was painless - and the wait was pretty short.

"You show up, they give you a number and call you up one at a time. They've got a gunsmith on site who goes over it with you - and I reckon they're being pretty fair."

A police spokesperson says they've only had one dispute over price so far, and it was able to be peacefully resolved.

But not everyone is happy.

One seller says most of the people he's spoken to are responsible gun owners - and annoyed they have to be there at all.

But he says he can't fault how police are handling the unique and new situation.

"I think the Government is over-reacting, and police are having to mop up the mess they've made."