What bead/tap for shotgun?

[Fortkevin2]

I've got a 12 gauge barrel that I've cut down to 18.5". Looking to tap a new hole for the bead. What tap size and bead height do you guys recommend?

http://www.brownells.com/.aspx/pid=18591/Product/SHOTGUN-SIGHT-BEAD-KIT-C-WITH-SHOULDERS

This barrel will be on a Survivor Stock set and will be my camp gun. Should I go tritium??

http://www.brownells.com/.aspx/pid=6846/Product/TRU-DOT-DAY-NIGHT-SHOTGUN-BEAD

OR

http://www.brownells.com/.aspx/pid=19914/Product/TRITIUM-SHOTGUN-SIGHT

[zombiehunter83]

Have you considered the stick on sight from TruGlo. Amazon has them for around $20 red or green.  Just thought I would throw that out there.

http://www.amazon.com/Truglo-Defense-Fiber-Optic-12-20Ga/dp/images/B004Z5BY8S/ref=dp_image_z_1_0?ie=UTF8&s=sporting-goods&img=0&color_name=1

[Brewster]

We recently cut down a 12 ga barrel.  We put on a .130 Williams brass bead (unshouldered) into a 3-56 hole drilled with a #46 bit.  Pretty easy with a cross-slide vise on the drill press, a centering devise to get top dead center, and a good torpedo level to plumb and level the frame and barrel.  Easy enough for a 15 yr-old to do, with supervision from grandpa.  Start small and work up if you're not satisfied with the little bead.
 
When we cut the barrel down, we saved the drop in order to get the cross-slide vise dialed in on the nuts.