Paul Holmes, 50, of Station Road, Holme, was sentenced at Carlisle Crown Court after pleading guilty to 14 firearms offences on Monday June 6.
He had previously pleaded guilty to two offences relating to the unlawful possession of handguns.
Police said it was the biggest firearms seizure in the North West since 2008.
The prosecution follows a joint operation led by TITAN (the North West’s regional organised crime unit), assisted by Cumbria Police and the National Crime Agency (NCA).
Raids were carried out at the defendant’s home address, a farm outbuilding in Milnthorpe and a garage in Devonshire Road, Morecambe (both also owned by Holmes).
During the search in Holme officers found a well-equipped workshop containing various machines and tools believed to be capable of use in manufacturing firearms. There was also equipment that was for use in reloading bullets and two handguns.
The haul of illegal firearms and ammunition seized Milnthorpe included sawn-off shotguns, rifles, a handgun, disassembled shot guns together with bullets of varying calibres.
In Morecambe, a large amount of shotgun and rifle ammunition was recovered, making a total of more than 2,400 rounds of ammunition seized in the raids.
Joanne Edwards, Detective Superintendent at TITAN, said: “I am delighted with today’s sentence and I think it sends out a strong message that those involved in the manufacture of firearms can expect no leniency from the courts. This massive haul of weapons recovered from Paul Holmes posed a direct threat to our communities and I am sure it is shocking to some that such a large amount of guns and ammunition were recovered in a quiet rural location.
“The recovery of these weapons is a direct result of a close working relationship between Cumbria Police and its communities, and the close working relationship between Cumbria Police and TITAN.
“TITAN’s mission is to tackle serious and organised criminals that have the greatest impact in the North West. Many of TITAN’s operations have a focus in the inner cities of Liverpool and Manchester, but this seizure just highlights that the threat of organised crime spreads across all our communities.
“This is the largest seizure of firearms that TITAN has made since its inception in 2008 and represents a nationally significant find. The communities of Cumbria and the North West are far safer tonight now that Paul Holmes has been imprisoned.”
Andrew Slattery, Detective Superintendent at Cumbria Police, said: “All the officers and staff in Cumbria Constabulary work hard to ensure that our communities are safe places in which to live and to visit, but Cumbria is not a safe place for organised criminals to conduct business.
“We take the threat from illegally held firearms extremely seriously and work hard with all our law enforcement partners including TITAN to target those posing the greatest threats to these communities.
“I am very pleased that through our joint policing efforts we have been able to deal effectively with this particular threat and remove illegally held firearms from circulation.
“The imprisonment of Holmes should serve as a deterrent to others who are tempted to become involved in organised crime – if you commit organised crime in Cumbria you will identified and you will be prosecuted.”