Ysterhout Dot Net
Barrel length limits powder choice for ELR.
For ELR, more velocity is better, but comes at the penalty of pressure.
Ideally, pressure must peak at the point before bullet exit from the barrel.
If the powder is too slow, it will not reach it's peak before the bullet exits the muzzle, and powder will continue burning after that point, resulting in muzzle flash and or excessive concussion, as observed from some short barreled BMG rifles.
If the powder is too fast burning, pressure peaks to the maximum with less powder, imparting less energy to the bullet, causing lower velocity.
The slowest burning powder that gives 100% burn in the barrel length with the chosen bullet is where to aim for. There are more powder choices with a longer barrel, which affords the possibility of maximising case fill, powder burn and muzzle velocity more easily.
