What's going on???

[LehighBrad]

I just inletted a small Queen Anne lock on a pistol project I'm currently building. After making sure ALL the necessary wood has been removed for the internal workings of the lock, main spring, bridle, sear arm, etc. With the lock set into its inlet and held there by hand everything works great with the trigger....half cock works, full cock works, and the trigger has very little slop in it. The trigger pull is a little heavy, but I'm happy with it. The problem is...when I turn in the lock plate screw snug that holds the lock into the gun, my half cock position no longer works!!  However, if I loosen the screw just a bit (not even a 1/4 turn) everything works just fine, but a teeny tiny gap (.010??)appears between the pan basin and the side of the barrel at the flash hole! Is there something being torqued out of kilter that's causing this?? Or is there some wood somewhere that I need to remove yet?? I've taken this lock off and on dozens of times and I'm puzzled?? I see nowhere where any wood is affecting the internals....even using black soot to cover the parts, I see no place where the workings are touching wood. 

[smylee grouch]

Make sure the sear arm hole is deep enough and there is room under the sear.

[E.vonAschwege]

On occasion, tightening the bolt that last 1/4 turn can rack the lock in its mortise, if the mortise and barrel flat aren't mated just right with the lockplate.  This will in turn angle the sear arm downward, causing it to rub on the wood.  Soot your entire lock and cycle it with the lock bolts properly tightened, then check with a light at the bottom of the sear hole for rubbing.  There should be no gap whatsoever between the pan and the barrel.  Also remove the trigger and then try it again just to make certain the trigger isn't keeping it from engaging half cock. 
-Eric

[rsells]

I would black the component side of the lock with soot.  I use a kerosene lamp turned up until a lot of soot comes off the flame.  Assemble the lock in the stock, tighten the screws and try to cycle the cock through the different positions, and remove the lock and look for witness marks on the wood and bright metal showing through the soot on the lock.  It should tell you what is touching and causing the problem.  I run through this process a bunch of times on each gun to make sure I have sufficent clearance.  Issues in the sear sounds like the problem when the screw is tightened.  I had the same problem on the Hawken I finished last week.  I trimmed the sear length back a bit to fix the issue.
                                                                                  Roger Sells

[Pete G.]

It is possible that the final tightening of the lock is tipping it slightly and causing the sear to contact the top of the trigger.

Try removing the trigger then install the lock and tighten the screw. Check it again. If it works then your problem is the interface between the trigger and sear.  If that is the case then the fix is simply to lower the trigger bar slightly.

[flinchrocket]

Just a question, but could the tipping be caused by the lockplate not being inlet deep enough? If there is a
gap between the barrel and pan when the lock bolt is loose it may be pivoting on the ends of the plate.
When the bolt is tightened up it forces the sear down on the trigger.

[frogwalking]

Another possibility is that the side of the stock where the lock is inlet may not be exactly square with the barrel.  This could cause the opening of the small gap between the lock bolster and the barrel flat when the sidelock screw is tightened.  Another possibility is the lock inlet may be a small amount too deep at the bottom.  This could result in the lock tipping slightly, and maybe the sear arm contacting the end of the hole in the stock. These issues can drive one nuts. 

[Micah2]

Probably not the case, but make sure the cock or jaws are not binding against the stock.  This is easy to overlook if you are looking for an internal problem, it could be external.

[LehighBrad]

Once again I thank all of you......turns out the very tip end of my sear arm was, in fact, contacting the wood ever so slightly...once chiseled out, everything works perfectly and no gap is seen between the lock bolster and the side of the barrel!! Thanks again guys.

p.s. Micah....my hammer WAS contacting the lock panel a bit too....which was what was causing the gap at the flash pan I believe. Thanks.