Ridgerunner,
Your description indicates that the cartridges do not seat fully into the revolver chambers. This is usually caused by bulged cases or improperly crimped bullets
1. The bullet base may have bulged the case, causing your chambering problem. Check that all rounds drop freely into and out of the chember when loading/unloading. They should not require force to chamber.
2. If the case mouth is crimped too hard into the lead bullet, or if the crimp is not aligned with the "crimping groove" the case can bulge at that point, and prevent easy chambering. Sometimes the maximum LOA is exceeded when using the crimping groove. If that happens on lead bullets, you miss the crimping groove and bulge the cartridge case. Crimping on jacketed bullets is easier because a "cannelure" is provided to give correct LOA.
3. Finally, your description of not being able to cock the hammer may be due to either bulged cases or protruding primers. Make sure that all primers are seated firmly to the bottom of the primer pockets. A protruding primer can cause your revolver to "chain fire" with REALLY bad results!
HTH
John