Half cock issue

[levers]

1860 carbine serial 48333 in nice condition. Half cock notch was warn but I was able to work the tumbler and both notches work fine when the lock is out of the gun. However when I put the lock in the gun, cock it and pull trigger it's good but the next time I cock it the half notch slips. Any smith types on here that can help? Thanks.

[DJ]

Since the lock works fine out of the gun, I would look for something in the inletted of the stock that is rubbing on the sear or the trigger.  Could be swollen or damaged wood, the lockplate being tightened too much (either recently or over time) or perhaps dirt or grime.  A little side pressure on any of the moving parts or a sliver that gets in the way can affect reliability.

[Blair]

levers,

The upper part of the Spencer "sear" arm, (the part the trigger works on) has a radius cut into it. This is because the "outer magazine tube" will not allow the sear to move up high enough to function correctly.
Look to see if your sear has this radius? If it does not, then you have a "Sharps" sear in your lock.
I hope this helps.
My best,
Blair

[levers]

Thanks fellas.  Turns out the wood had shrunk and the inlet portion of the stock near the sear was rubbing the sear just enough to not allow it to reset when the gun is cocked.  I removed just a bit of wood and all is good to go.