Trigger fits

[rallen]

I need the experts help on this, because the trigger/sear relationship has given me fits.  I have a Chambers Virginia lock. It is well tuned and cycles cleanly when mounted without the trigger. The sear at full cock is just a hair above half-cock position. I have the scribe lines to prove that. Whenever I file the trigger and it engages at half-cock, and I continue with a smooth file, I cannot get the full-cock position to engage, but I end up with slop at half cock.  I double checked the the mortise for any clearance problems and there are no marks inside.
Any ideas on what to look for next?
Thanks
Ryan

[Dave B]

Ryan,
So what you are saying is that you have no play in the trigger as you pull it back towards full cock but its very loose at half cock(engaged half cock) but the sear will not engage the full cock notch. Is that what you are saying? If you don't have a one position sear you will always have one position where you will have trigger play. It sounds to me like you still have to lower the trigger blade contact point with your sear to allow the sear to engage the full cock notch. I have seen where a thin spring steel wire can be used to keep the trigger from flopping around at half cock when in this situation. Its kind of like the ones the English use on their SXS triggers. Its a bit of a challenge to make that work on a trigger pined through the stock vs on pined through a trigger plate.

[Don Getz]

I agree with Dave above, either your trigger is too high to allow it to go into the full cock notch, or the sear is being held
up by wood......it has to be one of the two...........Don

[bob in the woods]

Funny..I just had the same thing happen on a gun I built last year. It was very humid here, and the gun wouldn't engage full cock. I drilled the sear hole deeper, and the problem was solved. The very tip of the arm was rubbing just a tad, but enough to give problems.

[James Rogers]

If I were a betting man, I would say it's having to do with wood binding the cycle in the mortise . Ask me how I know. 

[rich pierce]

You can live with a little jiggle.   

[fm tim]

"The Gunsmith of Grenville County" by Peter Alexander has a full description of adjusting the tumbler to get the sear to lie at the same place in all 3 operating positions (see pp 84-88).

[rallen]

That's true Dave and Don etc. There is no play when at half-cock which engages and is tight. When I continue to file to get the full cock to engage, then there is plenty of play at half-cock. I would have thought that having the half-cock just a hair below the the full cock would create the 'play' at full cock and allow the sear to engage at full. It's probably true that it is either wood or metal which I will check. Any other thoughts and advice?

[Long John]

Take some cotton lamp wicking and put it in a tin can with a little olive oil or other "lamp oil" in it.  Light the wick and soot the back side of the lock.  Carefully install the lock and cycle.  Remove lock.  You will see what is hanging up.  Keep in mind that if the mortice for the bridle is not quite right it can hang-up the fly and give you such fits.  Don't ask me how I know!

Best Regards,

John Cholin

[rallen]

Thanks guys for confirming some sleuthing. I stabilized the slop on the trigger and now have things almost working properly. I will try resooting the back of the lock to see if I have any contact with anything and double check the fly before I take out the smooth file again. By far the most finicky and error-prone part of putting a rifle or fowler together. Sounds like I'm not alone.
Thanks
Ryan

[Roger Fisher]

You can live with a little jiggle.   

Eye do