The N500 series of Vihtavuori propellants provide the utmost in performance for added velocity and range with heavy bullets. Nitroglycerine has been added to the traditional single base powder to get better energy content. The series offers five different reloading powders with different burning rates. N550- Burning rate is like with N150 and close to IMR 4350 and Reloder 19. Good choice for more powerful loads for 6,5x55 SE, .308 Winchester, .30-06 Springfield and for many others.