Most blackpowder poured in a line on the ground burns in a flash. A rifle smokeless powder burns slow in the same test as performed when I was about 10 years old. 
OK, that's a test in open air. Propellants have burn rate coefficients (the rate under steady pressure, like in the open air), and they have burn rate exponents (the rate at which they burn as pressure increases).
So, does BP simply have a very high burn rate coefficent, but a very low exponent? Pistol powders like Titegroup have a very high exponent, hence they are very sensitive to weight increases in powder or projectile.
I feel like I'm answering my own question, but it's never been confirmed. Why does BP burn so fast in open air, and not blow a gun bbl up as if it were loaded with 120gr of pistol powder?
OK, that's a test in open air. Propellants have burn rate coefficients (the rate under steady pressure, like in the open air), and they have burn rate exponents (the rate at which they burn as pressure increases).
So, does BP simply have a very high burn rate coefficent, but a very low exponent? Pistol powders like Titegroup have a very high exponent, hence they are very sensitive to weight increases in powder or projectile.
I feel like I'm answering my own question, but it's never been confirmed. Why does BP burn so fast in open air, and not blow a gun bbl up as if it were loaded with 120gr of pistol powder?
