Rcimp,
I'm going on memory here...on a factory head that accepted the little bulb and nut, the seat of the hole had a nice soft radius to it that fit the flange on the bulb. The nut that was captured by the capillary tube forced the bulb down onto the seat and mechanically sealed the whole thing. The nut wasn't a tapered pipe thread but merely a means of compressing the whole mess together.
I just thought if the bulb was assembled with brute force against a sharply machined bushing that it might split or break the bulb and let all the magic moose juice out, which would spell instant death.
Stuart
