The limiting factor is not force or velocity but energy. If the pellet retains its original mass, the kinetic energy imparted by the explosion won’t be enough to propel it to any kind of useful distance. If the pellet’s mass drops proportionally to its size, the explosion will accelerate it to a sufficient velocity, but upon exiting the barrel, the sudden increase in mass means it would have to shed a lot of its velocity to conserve its kinetic energy.
Truly, the question is whether magic can violate the laws of thermodynamics, and how that would affect entropy.
The limiting factor is not force or velocity but energy. If the pellet retains its original mass, the kinetic energy imparted by the explosion won’t be enough to propel it to any kind of useful distance. If the pellet’s mass drops proportionally to its size, the explosion will accelerate it to a sufficient velocity, but upon exiting the barrel, the sudden increase in mass means it would have to shed a lot of its velocity to conserve its kinetic energy.
Truly, the question is whether magic can violate the laws of thermodynamics, and how that would affect entropy.