Shocking footage has been uploaded online showing an elderly woman holding what is believed to be a "pump-action shotgun" and shouting "send our your martyrs".
The woman, who is a grandmother, is seen dancing and singing as she waves the gun.
An ammunition belt is seen draped over her shoulder.
Laughter is heard ringing out in the background as the elderly woman, purportedly a Traveller, poses with the gun. The clip was apparently filmed in a caravan in Dublin.
She is believed to be intimidating a rival Traveller clan, the Irish Daily Star reports, as she shouts: "Send out your martyrs!" - while cocking the gun.
According to the newspaper, security sources are said to be concerned after confirming the firearm is likely a real weapon.
"This is a very dangerous weapon and should not be played around with like this," a source said.
"There are a number of Traveller feuds going on at present - and while this might be some sort of joke, it is certainly no way for an elderly woman to set an example.
"But it shows how ridiculous it has gone that an elderly lady like this can get her hands on a lethal pump-action shotgun."
Armed with guns, knives and bombs two Traveller gangs have issued a stream of video threats against each other in recent months.
The videos, one issued from a Dublin-based gang, the other by a gang from another part of Leinster, appeared several weeks ago and threats of serious harm were issued by both sides.
There has been an ongoing feud between both gangs that has resulted in assaults but this latest pair of videos shows that the dispute may be entering a new, far more serious, phase.
Chilling footage showing of men waving weapons such as automatic weapons, machetes and knives were uploaded online. Gardai have been actively trying to keep a lid on the rising tensions.
Speaking last night, Sinn Fein TD Dessie Ellis said he was appalled an elderly lady would have access to a deadly weapon such as a shotgun.
"I am shocked and appalled at the thoughts of anyone having a weapon like that - this would be extremely worrying.
"I would hope that the gardai would be able to identify the people involved in this and to confiscate their weapons."
He added that feuding families should be urged to talk out their problems through an intermediary.