Not sure on a B30, but since its an extension of a B20, i offer the following:
There are 2 sizes of the injector seals, the thicker one being used when there are fibre insulating washers used to lessen the heat soak to the injector from the head.
Suspect you've got the wrong ones.
see a description on the Iroll motors website:
http://irollmot.ipower.com/oscom/ind...sort=3a&page=3
I would imagine they're the same whether B20 or B30. Give them a call and they can confirm.
Edit: noticed on Skandix site they list a 419785 seal, may be the larger one.
http://www.skandix.de/en/spare-parts...-injector/596/
Check your local Volvo dealer, they may be able to get them.