Just did a test with Gun Overdrive level 10.
Power shot was around 19k (No crit) [This is showing the damage comparison]
Regular shot with gun overdrive off was around 8k.
Regular shot with gun overdrive on was around 10k.
Mastered would give it another 51%
So the damage would be around 14-15k with it mastered.
I own a level 7 pearl pistol.
Thus saying, you need a higher refined gun to do adequate damage.
(This applies to people such as myself who don't know how to use timed crits)
I used a master's authority to get rid of the skill in place of Sharp Sense.
I was severely disappointed.