OK, from many years of doing "trigger jobs" or lightening trigger pulls on Original and Repro WBTS Muskets and Revolvers - I have found there was/is a LOT of WRONG information on how to check half cock notches that will actually DAMAGE the half cock notches and/or sear faces.
On one of the very first trigger jobs I did in the early 70’s on an inexpensive Italian lock, a customer brought back a musket I had worked on for some time, claiming the trigger pull had “gone to heck” and other problems. When I took the lock off the gun, I found BOTH the sear tip and the half cock notch had been broke off. Then I asked the owner what had been done to the musket after I had returned it. He told me “A Friend of his had checked the half cock notch and it didn’t work.”
So I asked him how his friend had checked it. He informed me his friend had pounded on the hammer with the heel of his hand against the hammer while it was on half cock until the half cock “didn’t work anymore.” I informed him his friend had just ruined the sear and half cock by doing something that was expressly forbidden by the Civil War Ordnance Manuals and showed him the section in my repro copy of the U.S. Ordnance Manual that talked about it. I felt sorry for him because he did not know any better and informed him he would have to pay for a new sear and tumbler, but I would do the trigger job again for free AS LONG AS he did not allow his friend to “do that BS test again.” His friend came up later rather belligerently that he had not done the test correctly, so I pulled the Ordnance Manual and showed him. His friend tried to bluster his way through, but fortunately the Main NSSA Inspector of Ordnance was there and said I was right and he was wrong. I asked "his friend" if he was such an expert, why hadn't he done the trigger job?
The CORRECT way to test the half cock on a musket had always been to put the hammer on half cock and turn the musket upside down. Then one put/s the trigger finger on the musket and allowed/allows the weight of the musket to be suspended by just the finger on the trigger. If the half cock notch held, then it was in correct condition. The same thing was/is done on revolvers to check the half cock notch by placing a finger on the trigger and holding the revolver muzzle down. As long as the half holds the weight of the revolver without pressing more on the trigger or pushing the hammer, then the half cock is working.
Now with a revolver, if when the hammer is on half cock and one pulls the trigger hard enough OR beats/pounds on the hammer, you can always cause the sear nose to slip out of the half cock notch and/or bust the sear tip of the trigger and/or the half cock notch of the hammer ”“ especially with some Italian revolvers where the parts are not made as good as the originals. That is NOT a valid test of the half cock notch and is actually doing damage to the parts.
OK, had to mention these things as it sounds like you may not have been checking the half cock correctly.
Yes, you need to take the revolver apart again to see if there is damage to the nose of the trigger or the half cock notch on the hammer.
If there is no noticeable damage to either part, then you just experienced why I mentioned earlier that a new hammer and trigger “may or should fix the problem,” but it is not CERTAIN it will fix the problem because you often have to adjust new parts to fit in repro revolvers. IOW, the parts are often not a “drop in fit” when you get them ”“ which sounds like it may be the case with your new trigger and hammer.
Zonie is correct there may be a burr or sharp edge on the half cock notch or the sear face of the trigger that is not allowing the sear face of the trigger to enter the half cock notch correctly. This was part of the reason I mentioned earlier using Hard Arkansas or India stones to get rid of burrs or sharp edges, before you put the parts in the revolver.
We are also assuming you actually received the correct parts for your brand of revolver and not parts made for another Manufacturer’s same Model of Revolver as yours. Parts made by one company will often NOT fit in the revolvers made by some other company, as the tolerance for the parts often are that much different.
Further over the decades, some manufacturers changed tolerances as time went on, so more recently made parts may not fit even their earlier revolvers without adjusting/tuning. This is why many gunsmiths recommend when buying a new revolver; that you immediately buy a new trigger, hand & spring, hammer, and trigger spring ”“ because you eventually are going to need them and later replacement parts may not fit.
Now IF as some others have mentioned that the sear nose of the trigger is not entering the half cock deep enough as it should and the problem is not a burr or sharp edge, then the sear notch has to be opened up to allow the sear nose to enter correctly. This is normally done with either stones or a combination of diamond files and stones, BUT is often beyond the ability of the Hobbyist to properly adjust and should be done by a qualified Armorer or Gunsmith. However, once you go taking metal off a hammer or sear, then you are responsible if the parts don’t fit. If that is what is going on, RATHER THAN doing the work yourself and risk ruining the parts, I would contact the company you got the repair parts from to see if they have a hammer that is made for your revolver with a wider half cock notch.
Finally, your only option to fix the revolver may be to have a qualified Armorer or Gunsmith fix it.
Gus
