I have e-mailed Macarri about a synthetic piston head for the B55 and got the reply that if the piston was machined like a Diana, one of his seals would fit. Wasn't very clear about how the piston should be machined. Here is the message

Dear sir,
Sorry we do not make any. If you turn the piston head down like a
Diana,
then you can fit an Apex small.



Thank You!
Karen Hughes- Sales
ARH
www.airrifleheadquarters.com

Anyone know how you turn down the piston head?