smallest carrier you say?
Does it leak when you hold the trigger?
Have you added enough oil? the carrier o-ring might just be dry.
oh, and make sure you didn't put the carrier in backwards... I've done that before
the inner white o-ring should face the rear of the valve.
otherwise, you might just need a new carrier inner-oring.. which of course would require some break-in. Is this a new o-ring? Might just need oil and a bunch of dry-firing to break-in.