Thread: Is it Pressure or Powder Capacity?

Originally Posted by Marty Henry

I don't know for sure but I suspect that a slower powder which delivers the same amount of energy over a slightly longer interval and we are talking milliseconds here might actually prolong the peak temperature. Fact is barrels erode, high velocity coupled with large wodges of powder will make it happen faster.

I read the Speer reloading pages you attached @Marty Henry.
They put it down to the gas core temperature under pressure in relation to the inner surface steel temperature that causes the erosion.
That is why the throat erodes the worst as that is where the gas core temperature is the highest. As the bullet passes along the barrel the pressure and temperature decrease as the space behind the bullet grows to fit the expanding gases.
So it seems it is due to gas temperature and pressure NOT cartridge powder capacity (ie if there is a lot of powder but the gas temperature and pressure, once it ignites, is not that high, then there is less barrel erosion).

An interesting aspect is that they state that all the powder is burned and transformed into hot gasses at around 9" of barrel length (they do not say what cartridge they base that on). This means everyone who says you need at least 16" to 'burn all the powder" is incorrect and that the 'muzzle flash' must be the gasses not burning powder.