Would someone please explain what kind of lock this is? Is this a preferred action type, or was it preceded or replaced by something else? I'm not referring to the gun in my avatar, but rather to 1800's rifles and pistols. Thanks!
Back action locks have the mainspring behind the tumbler, while front action locks like those in your avatar have the mainspring in front of the tumbler. This pic from the Track of the Wolf website illustrates it:
This is a modern made L&R lock.
Back action locks became popular in the mid-19th century and were common up to the end of the percussion era. Some folks think they are faster than back action locks. They were also commonly used on shotguns.
A modern made rifle with a back action lock is the Pedersoli Tryon.