Suppressor Velocity Boost in Relation to Caliber Size

[General RE LEE]

I have a Banish Backcountry 30 caliber suppressor. I get a 30-40 FPS velocity boost with my 308, about 20 FPS boost with my 6.5 Creedmoor and almost no boost with my 6mm ARC.

Anyone notice the biggest velocity boost with calibers that match the suppressor?