Aren't we confusing friction and resistance?
Friction is unpredictable and the guns we are shooting are virtually friction free when they leave the factory, after all the manufacturers have been at it 8 hours a day for the last 300 years!
Then we get our hands on them and bguger em up.
They pack them with a thick gooey grease for a reason. To create a constant resistance whilst managing recoil.
Now we require, and try to strive for a little less recoil, after all these are perfect sporting rifles and are not specifically designed for our purpose.
So to "tune" a gun we are trying to reduce spring compression and thereby recoil whilst preserving kinetic energy
To remove all the resistance from the working parts creates uncontrollable recoil and inconsistency and will certainly be temperature sensitive.
A car becomes very unpredictable if you just rely on the springs, so they add shock absorbers to create resistance and manage the recoil of the springs. A bit more technical as you haven't got a constant, but a similar principle.
So it all comes down to optimizing the resistance of the piston and the predictability of that constant velocity to make it do the exact same thing time after time.
Sadly, when you transfer or convert any energy you lose efficiency. We require a small amount of compressed air for our ultimate goal and that's why you need a boring PCP.
Because I'm without a intelligent name