Sear issues

[Sawfiler]

Using an RE Davis Colonial American lock on my current build. Somehow in the course of fitting the lock the nose of the sear snapped off where the half cock notch catches. The little bit of the nose which  the fly usually lands on to prevent the sear from catching at half cock did not snap off.  I was trying to be very careful with the lock so I am not sure how this happened. What was I doing wrong to break off the nose of the sear? I never dropped the cock from full cock without slowly letting it down with my thumb. Only function tests I had done was snapping the lock maybe 3 times to be sure my trigger was working correctly.

Second question - I assumed this was my screw up so I ordered a new sear and dropped in it. Back in business. First time I function test the lock the sear bar snaps off. Is there a tempering step I was supposed to have done that I missed out on or did I just get an imperfect casting? TOTW's website lists the sears they sell for this lock as tempered, was I wrong to assume it was ready to be dropped in and go? What can I do to prevent this next time?

Third question - If I was to try and make a new one should I use a steel other than mild steel? Or is this appropriate as long as I case harden it? Spending $20 plus shipping on new sears is getting expensive.

[Bob Roller]

Making a new sear isn't hard but I speak from long experience.
I use O-1 but 1018 case hardened will work.The original broke
because it was too hard.I have NO idea what these production locks are
made from regarding internal parts.
If it's a new lock I would think a new sear could be had free of any charge.
Even if it's NOT new a replacement should be free if the sear is unaltered.
Bob Roller

[Stoner creek]

I had an issue with the same lock. What happened is that the seat caught and hung up on the fly when released from the full cock notch. I had to reduce the height if the fly to a point below where the sear nose was hanging up. I did it with my belt sander and did not have to go through the normalizing/re-tempering process. Took about 5 minuets. Give Tim at RE Davis a call and explain the problem. He’s probably going to replace your broke part. I hope that helps.

[rich pierce]

I see a lot of tempering issues on locks. Recently had a lock where the frizzen spring could not be filed - but the tumbler and sear could. Because I polish every part, I can tell how hard the parts are and often re-temper or re-harden and temper as needed.

[jerrywh]

 I have never had trouble with Davis locks but have had with others.  If you get another new sear temper it to 600°  or a dark blue color. I have had to do this on several L&R locks.

[Nordnecker]

I've only had a 1 broken part on 1 lock and I BROKE IT. I called the maker and he said send the whole lock back to me. He said it will spend more time in the mail than it will in my shop. He replaced the broken part, fit it to my lock and sent it back to me free of charge. Turnaround was 5 days.

[Sawfiler]

Had not thought of trying a file on them to test hardness. I had polished some of the internals with sandpaper and I do not have a good enough feel with metal yet to tell hardness with just sandpaper. After I got home last night sure enough a file wouldn't scratch them. I guess I will call today to see about a replacement, and then be sure to temper it before I drop it in.

[D. Taylor Sapergia]

I've got files like that too...think I gave them to Daryl.