Yup, what he said :-)
I use a super fine applicator. I was turned on to this method by Darren Scannell, who won 1st in the 1/350 ship category at the Nats last year with his HMCS Toronto...once the ends are tacked into place, just use capillary action and run a bead right down the length of the rail. It's never failed me...
Go to any R/C airplane shop and get a section of Goldberg's Gold n Rod, it's the vinyl tubing guys use for push-rods for control surfaces. Throw out the inner section, and use the outer tubing section only. Heat it, and stretch it like sprue. Since it's a tube, it never loses the opening, and you can stretch it to the point that the super thin CA has trouble flowing through the tubing. About $6 gets you enough tips to last a year, about a 3ft. length. I can't remember the dimension, but it fits perfectly (unheated) over a bottle of Zap CA.
I've also experimented with tubes from spray bottles like Windex, etc., however, wait until the bottle is EMPTY, otherwise the wife will have your hide!! Those results are mixed, some types of plastic works, others don't.
Jeff