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.

 

[Slider]

I actually had a friend that had this problem, it turned out a screw had slightly backed out!!! I don't know where he had a Gun Smith repair it.

 

[Denvir Tire]

The good news is that the Greener bolt is properly fitted and actually engaging the rib extension. I agree with others that the gun just needs breaking in. I do close my vintage doubles gently but I am sure you won't damage a modern double by closing the gun firmly and letting the top lever spring drive the bolts home. When doing a quick reload while hunting you will want to just close the gun firmly, not slamming it closed. There is a difference. I think you should practice with the rifle just as you would use it in the field. Having a habit of closing it slowly or catching the brass may cost you in a tight spot. If it's your habit you will still do it while under pressure.

Very good advice