A curious occurrence

[longcruise]

Over the weekend I was shooting a CVA rifle that I had shot only once before with no problems but this last and second time shooting it had an odd problem.  Asking about it here because the collective knowledge and experience here might be able to set my direction for a course of action.

I'm not sure of the model of the rifle but it is a CVA with the typical CVA percussion lock and set triggers.  My previous shooting with the rifle gave fine performance with no hitches.  However, this next time out I had an occasional hanging of the hammer that prevented contacting the cap.  The hammer would fall just a tiny bit short of the nipple and cap. This could occur when fired with and without setting the trigger.  I suspected something wrong with the lock but I'm not sure what.

The height of the nipple seemed to be fine in the sense that when the hammer did drop all the way it hit hard and fired perfectly.  When it did hang up it was just shy of striking the cap.

Thoughts on this would be appreciated.  I know it's not a classy rig but it seems worthwhile getting it working since it is a very accurate shooter.

[Anonymous]

Hammer hitting or dragging on the stock?  A problem with inletting interfering with lock?  Maybe try loosing up the screws that hold the lock in place a bit, and see if that frees up whatever is binding.

[EC121]

Check to see if the mainspring or tumbler toe is hitting the wood under it.   Most percussion locks don't have a hammer stop like the flintlocks.  They depend on the bridle screw or nipple to stop the stroke.  You might also have a piece of dirt or wood between the tumbler and the bridle screw.  That would stop the hammer just short of the nipple.

[D. Taylor Sapergia]

If the bridle screws inside the lock have backed off (are not tight) the fly may have dropped right out or be so loose that it is not functioning properly.  Have you had the lock out to diagnose its function?  It sounds like the sear is dropping into the half cock notch in the tumbler as the hammer falls, stopping it from hitting the nipple.  If you continue to let this happen, your lock will be ruined...sear for sure, and possibly tumbler too.

[Semisane]

If the bridle screws inside the lock have backed off (are not tight) the fly may have dropped right out or be so loose that it is not functioning properly. ………………...

BINGO!

[J.E. Moore]

Make sure the top lock bolt isn't rubbing the inside of the hammer.

[Pukka Bundook]

I think Taylor has it.
My thoughts are the same.
One possibility is a worn full bent position, or the scear not engaging full cock fully.   If this is the case, the tumbler may slip from the scear  with very little movement, allowing the scear to catch the half cock notch.
If the lock has a fly, it should ride over this.  (Unless it fell out as Taylor suggested)

[longcruise]

The fly was my prime suspect and I inspected it when cleaning at the end of the day.  It seemed clean and seemed to be functioning.  I cleaned as well as possible but didn't check screws, etc.  Disassembling the lock while cleaning at the back bumper in a field probably would have a disaster.

I'm going to take it apart later today and inspect it while keeping all these comments and suggestions in mind.

[longcruise]

Well, earlier this afternoon I played around with it and couldn't get it to malfunction.   I cleaned it up some more and checked the screws and looked for signs of interference.  Nothing was apparent.  The tumbler screw had a bit more than 3/4 turn available.  Maybe a combo of a bit of  crud and the less than tight screw?

Hopefully this is the end of it.   It looks like it was a kit that was put together okay but that's all.  It shoots as well as I have ever been able offhand so it's going to get a refurbishing.

Thanks for the suggestions.   Can always count on the ALR crew.