how big is a bullet?
F = M X A
The force stays the same as long as every time you reduce the M you increase the A by equal amounts..
So a 50lb weight travelling at 10ft/sec2
will hit with the same force as a 25lb weight travelling at 20 ft/sec2
In other words the smaller the projectile the faster it has to move to be effective, a bullet won’t kill you if I throw it at you.
You are not concerned with force, but kinetic energy, which goes up as the square of the velocity.