Dammit!

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Col. Harrumph

Col. Harrumph

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What should I do?

I bought a junker BP rifle (I needed a project). All went well until I tried to fix the hammer/sear relationship: the sear didn't hold the hammer at full cock.

I worked on that for quite a while, and got the two to mate correctly. The sear held the hammer against strong thumb pressure. Yay! Time to surface harden the parts. I used TrackOfTheWolf's frizzen hardening compound with a MAPP torch, and it worked!

Then I reassembled the gun, and presto!... except the sear wouldn't hold the hammer. Again. DAMMIT! I need to re-cut the hammer's sear notch, but now it's hard. A file won't cut. (The sear itself is OK.)

I could buy a "new" hammer, Gunpartscorp.com has them. But then I'd be out $40. I have a Dremel, but the cutting wheel is too fat to grind a good notch. I could send the whole mess to Mark Novak (youtube channel "Anvil") but that would be admitting defeat and also cost megabux.

Tell me, internet X-perts, what should I do?
 
We annealed case-hardened steel in shop class (hammer heads) to rework them. I am neither a machinist nor a specialist in metallurgy, but I can't see any reason why you could not re-anneal the hammer, re-cut, and re-case harden.
 
Just buy the new part ... that's not admitting defeat, it's just taking a different, and a more sensible and more likely to succeed approach.
 
If you have a honing stone for a knife, it will grind the surface. Not sure if you can get the part onto a whetstone though.
Otherwise a5werkes is right, you need a diamond file. You can get a set of inexpensive diamond jewelers files online. They won't last as long as a good set like the ones above, but they will work for a little while, probably long enough to fix your sear and hammer.
You could also try a carbide welding tip cleaner but that's not really a good shape for what you're doing.

You can put the piece in a really hot oven or grill and get it up to around 500 degrees, then let it cool in air to temper it down.
 
You can probably cut through the hardened area fairly quickly , I doubt the hardened area is very deep at all, I'd give it a few minutes with a stone or small file. but I could be wrong. Good luck!
 
Col. Harrumph said:
What should I do?

I bought a junker BP rifle (I needed a project). All went well until I tried to fix the hammer/sear relationship: the sear didn't hold the hammer at full cock.

I worked on that for quite a while, and got the two to mate correctly. The sear held the hammer against strong thumb pressure. Yay! Time to surface harden the parts. I used TrackOfTheWolf's frizzen hardening compound with a MAPP torch, and it worked!

Then I reassembled the gun, and presto!... except the sear wouldn't hold the hammer. Again. DAMMIT! I need to re-cut the hammer's sear notch, but now it's hard. A file won't cut. (The sear itself is OK.)

I could buy a "new" hammer, Gunpartscorp.com has them. But then I'd be out $40. I have a Dremel, but the cutting wheel is too fat to grind a good notch. I could send the whole mess to Mark Novak (youtube channel "Anvil") but that would be admitting defeat and also cost megabux.

Tell me, internet X-perts, what should I do?
Click to expand...

<Clint Eastwood voice> A man's gotta know his limitations.</Clint Eastwood voice>
 
At the risk of stating the obvious: I have found such a situation several times where the fault lay not in the sear and/or trigger, but in one or both binding in the stock - the sear and mainspring can also suffer from stock binding. Since you know the lock works properly OUT of the stock, perhaps the fault lies IN the stock. Just sayin'...

PRD1 - mhb - MIke
 
The parts were inlet at the factory and do move freely. The problem is that the hammer's sear notch is too small, or they used an inappropriate steel in making it (the hammer is a casting). I should add that this is an old "Buggy Rifle" that Numrich (now GunPartsCorp.com) was selling 40-50 years ago. The old hammer was junk and had been bubba'd. Fortunately, a NOS part is still available at GunParts. I bought one. It worked great for ohmaybe 20 shots, then started failing as described in the OP above. I'd rather not buy a second one. The trigger, which includes the sear, is fine, I think. Here's pic of how they work together..
20201012_115457.jpg
The large notch in the hammer (on the left) is the half-cock and it holds fine. Its sear notch is so small it's barely visible. The fix, I think, is to cut it deeper, and for that I've ordered a 3-square diamond file from Brownell's. If it cuts through the hardened layer I introduced above, I'll use a knife-edge file I have in my tool kit to re-cut the notch. And then re-harden.
 
"What should I do?"

Trash can it and move on. Buy a decent kit to build a rifle if you need a project. Why waste your project time on junk anyway?
 
Blkhrt13 said:
you could try to anneal it where its too hard but you are likely to over work it when you try to harden it again.
Click to expand...
I love it when people post about things they have not studied. Case hardening, uses low carbon steel to which a thin layer of carbon is added (packed and heated in a carbonaceous material like "Casenite") and then quenched to hardened. That produces a hard outer "shell" (A.K.A. "case"), with a relatively soft inside as opposed to high carbon steel which will needs no carbon added and will harden all the way though. "Over work" (ing) it is not likely, but if heated to too high a temperature, the heat can make the grain structure of the soft inner steel to grow larger (weaken the structure).
 
Mild steel can also be case hardened with only an A/O torch. Use a highly carburizing flame and you can see the steel get a slick shiny look as it absorbs the carbon in the flame. I have used this method with quite a few parts. After quenching the surface is harder than a file.
 
Huh, didn't know that. Didn't matter either, as I don't have that equipment.... just a mapp torch. Track o' Wolf's instructions for their frizzen hardening compound do say to heat the part in a acetylene-rich mixture, but I just assumed that was to prevent a layer of corrosion from forming as the part was heated.
 
Last edited:
Think outside the box. If you know somebody with a router and a router table.... Buy the adapter collet to mount a 1/8 inch shaft cutter. Then mount a Dremel wheel or cut off in the router. Mount the router into a router table and make it into a makeshift surface grinder. Clamp the hammer into a block of wood and slide the wood across the router tables fence. That should keep everything square and unwobbly. Reharden. No annealing is necessary.
 
If you could heat it enough for surface hardening compound to work, you also have the equipment to anneal it again.

As above a stone can remove metal a regular file will slide across.
 
Actelyene (c2h2) being rich in carbon, a rich flame will drive more carbon into the steel surface
when case hardening.
You have to watch the flame tip as to how much oxygen to add, too much and all the carbon is burned,
and too little and you will have a smokey flame.
 
Well the TrackOfTheWolf hardening compound, which is meant for preparing frizzens to spark (the included instructions are very detailed and specific for this),
[this stuff: https://www.trackofthewolf.com/Categories/PartDetail.aspx/1017/1/TRU-SPARK-4]
does not work on an old "Hopkins & Allen" (Numrich) hammer. I wish Kasenit was still available, I've had good luck with that on other projects, but lost my dwindling supply in a move. Maybe Brownell's will have something.
 
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