Causes of 1873 binding?

[Story]

Howdy,
What are the most-likely causes for binding while cycling an 1873?

Lower lip missing/snapped off of the breechbolt face?

Hammer riding too low?

The firing pin rides hard against the hammer face at full throw. Also, has anyone ever noticed how many 1873 firing pins are snapped at the same point?

Thanks in advance for any suggestions.

[Grizzly Adams]

Would like to help, but need a bunch more detail in order to even start trying to help answer your question. As a beginning, are you talking about a Winchester 1873 or an Uberti 73?

1.) The cartridge retainer tab on the bottom of the bolt would have nothing to do with "binding." It would effect extraction/ejection. 2.)Actually, I have seen few "snapped" firing pins on any 1873/73.
3.) "Hammer riding too low?" Not sure what you could be referring too.......