While it would be technically possible, it would be a very bad idea. Going from 14gr. way down to 3gr. of what is undoubtedly a very slow pistol powder would reduce muzzle velocity dangerously and might very well lodge a bullet in the handgun's barrel.
Finding a reduced charge of the original powder that MIGHT reliably reduce muzzle velocity would involve:

1 Pulling the bullet so as not to deform it
2 Removing a very small amount of original powder
3 Recording how much powder was removed from the original powder charge
4 Replacing the bullet
5 Firing the bullet to observe and record ballistic characteristics

The five steps listed above are theoretical in nature.
PERFORMING THESE STEPS IN THE REAL WORLD WOULD BE EXTREMELY IRRESPONSIBLE!
PEOPLE HAVE PROBABLY BEEN INJURED OR KILLED AS A RESULT OF ATTEMPTING THIS!

No responsible person should ever reduce a factory powder charge at all, much less as drastically as you have suggested.
Tinkering with charges of a powder with unknown ballistic characteristics is always dangerous.

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