Between 1.10pm and 1.50pm on Thursday 10 July 2014, the offenders went to a property on Ross Lave Lane in Denton and climbed up onto the conservatory roof and climbed in through a first floor window.
They searched the property and then used a shovel to break open a gun cabinet.
Two shotguns and an air rifle were stolen along with cash and a large amount of sentimental and valuable jewellery.
Police are appealing for information and witnesses and would like to speak to a man and a woman who were seen in the area around the time of the offence.
Both people were white and slim. The man had short brown hair and was wearing a light blue shirt with the sleeves rolled up, light brown, khaki coloured trousers and dark coloured shoes. The woman had long straight dark brown hair and was wearing a peach or pink vest top with dark coloured leggings.
Detective Constable Ian Parker said: â€œWe are keen to trace a green Ford KA with chrome alloy wheels which was seen in the area around the time of the offence.
â€œTwo people, a man and woman were seen to get in to the car and we would like to speak to them as they may hold vital information to assist our enquiries.â€
Anyone with information should call police onÂ 0161 856 9484Â or the independent charity Crimestoppers anonymously onÂ 0800 555 111.