[chriske]

In handgun loads, what factor (if any) determines te amount of muzzle flash ?

Barrel length remaining equal, is it the amount of powder or its burning rate ?

[rcmodel]

Both to some extent.

But burn rate probably plays a much bigger factor because you use much more slow powder then you do fast powder. And you maintain higher bore pressure longer.

But the fact is, the flash is really not burning powder left to burn outside the muzzle.

It is the super-heated high-pressure gas release reacting to the much cooler air.

rc