The shotgun was presented to Aratoi by Carterton mayor Ron Mark, on behalf of the owner, and according to a report from Aratoi to a meeting this week of a Masterton District Council committee it had been appraised and authenticated by auctioneer Dunbar Sloane snr.
At this week's meeting, which was attended by Aratoi board chairman Frazer Mailman and Aratoi director Alice Hutchison, councillor Brent Goodwin said he had talked to a historian and the details on the inscription "just don't add up".
"There was no such person and no trip to England by Maori in that year," he said.
Ms Hutchison said research was continuing and that gun expert Tony Roseingrave had determined without doubt the shotgun was Belgian-made.
She said there was "very little provenance information", iwi didn't seem to have much information either, and the shotgun had no presentation case.
She said as far as Aratoi buying the shotgun was concerned "it is not likely we would invest a huge amount of money".
Wairarapa archivist Gareth Winter said yesterday checks had shown there was no Hamuera Tamaha Makupuku and, although typographical errors could be blamed it was very unlikely Mahupuku would have accepted a gift that had his name spelt wrongly.
In any event Mahupuku had not travelled to Britain in 1887 and at that time was a Papawai leader but had yet to become a paramount chief.
He was a firm friend of premier Richard Seddon but the date was six years prior to Seddon becoming premier.
"There was a contingent of Maori who visited Britain in 1897, not 1887, but Tamahau Mahupuku was not one of them," Mr Winter said. Although the train of events was not known it was possible someone long ago had tried to inflate the value of the gun by incorporating the inscription or it could have been the result of "misunderstood stories".
He said Wairarapa Archive regularly gets visits from people who have the wrong end of the stick or half a story which becomes embellished over time.
"I am not saying that this shotgun was never owned by Tamahau Mahupuku, it may well have been connected to him at one time," Mr Winter said.