The 2-56 or 0-80 #190 ball joints would work. I fly tons of r/c and love them.
Any gunsmithing shop will have a shotgun bead assortment, but the price of $7.00 is probably lower. Brownells or Midway will have beads- you can even get a tritium bead for night games...
Hobby shops also have the Gucci pink and blue tubing for the pneumatic retracs that works great on 'Cockers.