So I've known for a long time that handguns shoot projectiles whose hitboxes will apply a second hitbox on the general area where they stopped moving (whether it be through colliding with something or reaching its maximum range), and I also know that the second hitbox is the one that actually deals the damage (which is why handgun projectiles can't break plants until they've reached their maximum range or have collided with something nearby)...
What I don't understand however is how the "maximum" range of a handgun projectile works. Take any Magnus line handgun for example; while for the most part its projectile's maximum range is usually consistent (= less range than a Blaster), I've had times where the projectile visibly went further than normal (= about as much range as a Blaster).
Now whether or not this is a simple graphical inconsistency with no direct relation to the handgun's projectile range is something I haven't properly tested myself, but if not then I'll have to ask this question: "Can the range boost be exploited on a more consistent basis?"
The preamble about the hit boxes seems like a red herring. You are really asking:
A. Has anyone else observed that Magnus-style shots sometimes go farther than their usual range?
B. Is there any consistent way to make this happen?
And are you asking about regular shots or charge shots? (And no, I have not observed extra range on either.)