Can a heavy piston rob power?

[Barryg]

I'd say to raise power as they use the same spec spring for all calibres, it's so they can adjust the power easier, exactly the same idea that BSA use with washers in the Supersport/star.

So I guess the simple answer is that a heavy piston doesn't rob power unless using extremes

But just for fun I wonder what springer has the heaviest piston, my guess is a Patriot