The new barrel band is a plastic molding, although at first glance it's very difficult to tell if it's plastic or metal.
The barrel diameter is 15mm (same as all other models except the QB78 standard model).
And another point...
I'd say that the fit of the action into the synthetic stock is MUCH tighter than that of the wood stock versions. This means that there's more solidity in the feel of the gun. Not sure yet if this will be good or bad for accuracy. Or maybe there will be no change.
Archer Airguns Inc.