The enormous forces that build up in the barrel, cause severe wear to lands and grooves. Here you can see a close-up of the wear in three different barrels of 6.5x55 in front of the chamber after some 10,000 shots with Norma Diamond Line Bana, 3,700 with uncoated bullets, and 7,000 with Norma Diamond Line Fält.
Compare the results for yourself.
The barrel retains its accuracy more than twice as long when Norma Diamond Line is used from the outset. This is because Norma Diamond Line is coated with molybdenum disulphide and a protective layer of wax. Friction is reduced which means that the bullet travels further along the barrel before peak pressure is reached. The result is lower wear and improved accuracy.