Rival criminal gangs are being forced to share guns, analysis by police firearms experts has revealed.
The National Ballistics Intelligence Service (Nabis) has identified a "middle market" between users and suppliers of the deadly weapons.
Guns may be held in a central point and even "rented" to different sides of the same conflict, they said.
Detective Chief Superintendent Paul James said: "We see the same guns being used over and over again. Scarcity is such that they are exploiting that weapon, to lease and rent those firearms out. The same gun can be used by people on both sides of the equation. One gun on an estate can be used by people you would not expect to be allies."
Nabis, which was set up a year ago, brings together cutting edge forensic technology and police intelligence information.
Every time a weapon is fired it leaves a distinctive fingerprint on the bullet. Combining those marks with police investigations on a giant database reveals patterns of use across the country.
In most cases guns are tied to a particular area, but in some the same weapon has been linked to separate shootings hundreds of miles apart. Guns which have lain dormant for more than a decade have been found to reappear.
In its first 12 months in operation, Nabis has linked more than 350 guns with crimes. It has also played a key role in bringing down major armourers, including Paul Anderson, who supplied guns to the killers of Rhys Jones.
Mr James said cracking key suppliers means there are fewer guns on the streets and added it was wrong to suggest that guns can be bought cheaply and easily. He said: "It's a myth that you can go into a pub and pick up a gun for £50."
But he warned of a new threat from gangsters converting Russian-made Baikal pistols. They are converted to fire real ammunition and smuggled from Lithuania.
