Not exactly what you're talking about, but consider the following.
We manufacturer coated bullets. We use Hi Performance bullet coating. Out bullets are brinell 12.
When comparing lubed bullets to coated bullets, we consistently see velocities in the coated bullets higher than the lubed.
Also, for about 10 to 20 rounds, the coated bullets keep increasing in velocity.
Our only explanation is that the coated bullets are cleaning the barrels.
So be sure you take enough samples to make sure your setup has stabilized.