Guwahati: The mystery surrounding three artefacts - a gun belonging to Emperor Sher Shah and two swivel guns belonging to the Mughal river fleet or Nawara- which went "missing" for more than 70 years and were found four years ago, further deepened with the Archaeological Survey of India (ASI) still unable to match the exact date of one of the two swivel guns.

The guns were among 35 protected missing artefacts in India which were untraced for a long time.

Two of the items were found at a government circuit house in Chapakhowa under Sadiya sub-division, and another one at the sub divisional officer's quarters in Sadiya in 2014.

Four years after being found, the ASI now says one of the two swivel guns may not be the actual missing artefact as it doesn't match the other two which belong to the same period (Mughal period).

To ascertain the exact origin of this "unmatched" gun the ASI is now contemplating the help of experts, especially in the field of metallurgy.

"There are three guns. One belongs to Sher Shah, the other to the Mughal Nawara but the third which we have not been able to match is still a mystery. We need to know more about this gun and find out who it belongs to. We need to rope in experts to find out more about the metallurgical details of this unmatched gun," K. Amarnath Ramakrishnan, superintending archaeologist at the Guwahati circle of ASI, said.

In March, Ramakrishnan wrote a letter to the Tinsukia deputy commissioner to hand over the guns to the ASI as they are protected artefacts under the Ancient Monuments and Archaeological Sites and Remains Act, 1958.

The three guns were deemed missing for decades until the search for them was intensified in early 2014 when Lakshmanan S., the then Sadiya sub divisional officer became part of the search and conducted a research on the guns.

In that same year it was then soon confirmed by the Guwahati circle of the ASI that the two guns that rested in the veranda of the circuit house and another at the storeroom in the house were indeed the "missing" artefacts.

The first gun, considered to be that of Emperor Sher Shah, has the mouth of a ferocious lion engraved on it.

It is about 146cm in length and weighs around 58kg. The lion figure is about 13cm in length.

The gun has a 1cm diameter opening at the tail end of the cylinder which may have served as a point for ignition.