Sticky cases are normally associated with one of two things:
1) high pressure .357 Magnum loads, although in that case we're talking mild sticky where the ejector rod needs a firm rap with the palm (Google "stress fire" and "universal" revolver reloads - they differ from the older FBI reload i using the palm of the hand rather than the thumb to eject the cases for this reason).
2) a build up of carbon in the chamber due to inadequate cleaning or in the case of .357 magnum cases, build up of a carbon in ring in front of the shorter .38 Special cases after prolonged use of .38 Special, without adequate cleaning. Use a good powder solvent and bronze brush, let it soak an hour or so, and then repeat before cleaning with patches and powder solvent.
It's possible however that there's something not right with your ammunition, and the easiest way to check that is to try another brand of standard pressure .38 Special.
Worst case (and highly unlikely, as the cylinder tends to fail catastrophically instead) you've got some bulging in the chambers from massively excessive pressure. A bulge or ring in a chamber is much more common in a rifle chamber, where the pressures are much higher and where the steel is much thicker and will exceed it's plastic limit, without catastrophically failing.
