Three men were sentenced to a total of 37 years in prison on Wednesday for their role in running one of Britain's largest ever gun import rackets, according to Reuters. Robert Tyrer, 51, his brother Jamie, 36, and Kenneth Lloyd, 55, all from Manchester, were sentenced at Manchester Crown Court after pleading guilty to firearms charges earlier this year. Two other men will be sentenced later, while Greater Manchester Police are still seeking a sixth man in connection with the gun-running plot. The gang smuggled blank-firing guns bought legally in Germany into Britain and then converted them so they could fire bullets. Most of the guns were simply posted from Germany to Britain in large parcels. The plot was discovered after a parcel of 14 guns was mistakenly delivered to a shop in a Manchester suburb. Police believe the gang brought 274 guns into Britain and say they discovered enough raw materials at the Tyrers' home address in Manchester to manufacture thousands of rounds of ammunition. Robert Tyrer was sentenced to 19 years, Jamie Tyrer to five years and Lloyd to 13 years. Their arrests and convictions followed a year-long police investigation codenamed Operation Carbon. The gang sold the guns, which they bought for around 80 pounds, for 750 pounds after modification. Police have since recovered 109 of the imported guns.