Greener crossbolt third-bite lock behaving whimsical

[rookhawk]

The snap caps are the problem! Or at least how the snap cap fits. Or else why would it close easily and completely with nothing in the right chamber? Your right chamber is likely a little "shallow" at the case rim recess, or there is a small bit of dirt in there, or the snap cap rim is just too thick as suggested by Kevin P. My Merkel 140AE had a tiny bit of rust on the ejector shaft ( internal, out of sight ) that caused a problem with lock up and ejection. Removing the ejector and cleaning it, polishing the shaft a bit, and re-lubing solved the problem.

When things are new, remove all grease and replace with kroil that is low viscosity. When things are old and loose, cake it in good hinge pin grease. You did the right thing.