DuPont IMR-7828 A Top Slow-Burning Rifle Powder
We tested 9 different rifle powders with 13 different bullets, including the new Nosler Partition Gold bullet. The new Reloader 25 powder was, in our opinion, a disappointment.
The velocity of a bullet is a function of the pressure behind it, or the chamber pressure. Higher pressures develop higher velocities. That’s why a .30-06 shoots faster than a .30-30. Velocity is also a function of the length of time that the pressure is applied. A longer barrel shoots faster because the bullet stays in the barrel longer. That’s also why slower burning powders develop higher velocities. The hot gases generated by the burning powder push on the bullet for a longer period of time.
Chamber pressures are generally limited by the brass case to 65,000 psi (52,700 cup), although we’ve never tested a commercial load that “hot.” Belted cases may withstand a little more pressure t...