I have an old antique revolver that I need to either file the front sear or the part on the hammer where the sear catches so that they can fit together properly. Right now, if the trigger is released quickly the front sear will pass the notch where it is supposed to go in and then the single action won't work properly because it won't grab the front sear.

If I file either of these parts, will I have to reharden them or can I just file them down and put the thing back together? Also, which part would be better to file down, the front sear or the part where it catches on the hammer?

These parts are probably case hardened. If you remove that "shell" (a few thou thick) the hardening is compromised and the part will wear much quicker. Case hardening is not considered to be a DIY job.
If you don't know what you're doing in there (and it appears that you don't), chances are you will wind up ruining the trigger, hammer, or both.
For these reasons, my suggestion is to consult with an experienced gunsmith (if you can find one who understands revolvers)

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-jwk-
US Army '72-'95

I've made springs successfully which involves hardening and tempering. Would this be that much different? Also, that's what I'm trying to confirm, are these parts in fact case hardened? If so, is the front sear also usually case hardened?

If you have to ask.....................



Bruce

What's that supposed to mean? I'm just trying to get some information here. Yes hiring a pro would be ideal for the gun but that defeats my whole purpose. I want to learn to do it and that's why I bought this revolver broken. The only way that's going to happen is by doing it, not paying someone to do it for me. So can anyone give me a real answer about what exactly to do if I want to do it myself?

I could fix it another way by adding some metal on the front of the trigger so it can't travel as far foward allowing the sear to drop in at the farthest point foward the trigger can travel but I see that as more of a work around so I would rather hand fit the sears. Any pros out there suggest this method instead?

In answer to your question, if you need to remove more than a few thousandths of an inch, the case hardening will be compromised and it should be re-hardened after fitting. That said, I have never done so, therefore I can not be of any assistance to you. If you are handy, adventurous and have the time, money & patience, go for it! I would love to know how you make out if you do attempt the task.

I give you credit for even considering this; most people wouldn't. There are times that I have made a decision to attempt similar jobs on guns,cars, motorcycles, etc. and most are successful (some are not). In your case unless you have the proper oven and chemicals, even if you research the know-how part, it might be impossible to do, but look into it and let us know how you made out.

Good luck,

Chief38

EA,
It is my understanding that the sear is case hardened and yes you can file off enough material to expose softer steel so as was mentioned it would cause the metal to wear much faster. But tempering springs would be much like the process you would use to case harden the lower carbon steels. I would research the steel type used for the part you are going to case harden. I've put a link to a video that will get you started. The quality isn't that good and with my old hearing some of the explanation is lost but it will give you a place to start. It even looks as though the guy in the video is doing the same part you want to. I would not hesitate to try it you've already said you bought the guy to do the work on it and the worst that could happen is premature wear if it doesn't harden properly. After the procedure bring the part to a local machine shop and ask them to check the hardness for you. Explain you want it tested at the sear surface and not the whole part. It ain't rocket science. Go for it.

I forgot to include the link. I'm deaf and dumb!
AGI 320 Case Hardening Metal Parts - YouTube

You didn't mention the make of the weapon. S&W case hardened all their hammers & triggers. There are chemical compounds, like Kase-Knit (sp?) that will restore case hardening, but if the parts are color cased, the heat may destroy the colors. Color case hardening is NOT a do it yourself process, it usually involves potassium cyanide and some other toxic substances.

Your description of the front sear & trigger action is puzzling. I can't visualize what you're trying to describe. Pictures?

Frankly, a file isn't the correct tool to use on any sear I ever saw.

I would suggest using a stone rather than a file for this operation. Files tend to remove too much metal too quickly. It's very important to make sure the connection points are square to each other as well. See image below.



After checking the type of steel used in the parts, this surface hardening compound can simply and inexpensively be used to apply case hardening. Color case hardening will potentially be removed by this process.

One of the cardinal rules of gunsmithing is to modify the less expensive part first. Make sure you know which part (or parts) is causing the issue and go from there. A good resource book is Jerry Kuhnhausen's Shop Manual.

Good luck and post before and after pictures of your project.

David

Y'oud be surprised how little gun people know about their guns. Just not much good info on the net unless your are talking about which grips came with which gun and questions like that. There are people know the answers but you wont find them posting here, job security. I would guess the parts are case hardend, how deep I dont know.

It is an old Iver Johnson American Bulldog. Below are some pictures. Here is how they would aproximately be inside the gun. I didn't picture the hand and hand spring because they don't matter here but the hand spring is what is pushing the sear to the right to make it mesh with the hammer. The first picture is how it should be and the second picture is how it actually ends up if the trigger is pulled foward rapidly. If it is moved slowly, it ends up in the correct position because it gives the spring time to push the sear into the slot but if the trigger moves quickly foward then it moves past the notch where it should fall. My other solution to this was to add a bit of metal on front of the trigger so that the extra metal would hit the trigger guard not allowing the trigger to move as far foward thus not allowing the sear to pass the notch where it should sit. The correct soulution in my opinion would be to modify the sear though. What do you think?

Thanks, will use a stone instead.

I was looking at that product last night and was wondering if anyone tried it. It sounds simple enough. This might be a dumb question but I can't tell if it was color case hardened but if it was and I hardened it using this compound instead, would it matter besides it not having the color? In other words, does color case hardening do something significantly different from case hardening using this compound?

I used a previous version of that product called Kasenit. It really is as simple as it sounds. As with any other hardening process, you need to balance hardness with the risk of making the part brittle.

Not a dumb question at all. The colors in color case hardening is cosmetic. There are all sorts of formulas for different colors. Many of them are horribly dangerous, such as the ones that use cyanide. I'm not kidding.

David

OK, 'twasn't anything like I was expecting. The comment about "if the trigger is pulled forward rapidly" is a bit strange. Do you mean if the trigger return spring is allowed to push the trigger forward rapidly? Like if the trigger finger doesn't slow the return?

The position of the parts in the second picture makes it look like either the trigger isn't returning fully to it's forward position or the sear spring isn't powerful enough to drive the sear into position and prevent the trigger from rebounding. I lean toward the second possibility.

Slightly beveling the sharp lower left edge (where the lower tip of the sear is resting in the second picture) of the large hammer notch the sear is supposed to fit into may buy you some relief. It doesn't appear to really need to be such a sharp protrusion.

I strongly doubt IJ color cased much of anything. You might check references. The only difference is color case is purtier than plain case hardening.

Thanks for the very helpful information. I definitely don't need anything cosmetic as these parts can't even be seen unless it is taken apart. I guess I'll be placing another order with Brownell's. I just recieved an order from them last week so there goes another $12.95 in shipping. It always seems like I find more stuff I need after I place an order

I'm going to go with modifying and hardening only the sear and leave the hammer untouched since the sear recieves little to no impact, just a little friction.

There are promotional codes for Brownells occasionally. Last time I ordered from them I used a free shipping on orders over $150 code.

You may also want to consider replacing the sear return spring first. That may solve the problem without risking any other parts.

David

That's a good idea... Maybe i'll try that, it's going to be hard to make that little spring since it's a v with an "L" on one side but I guess it's just more practice

Have you looked in Numrich Arms/Gun Parts Inc.? There are some times where a couple of bucks on parts is much easier.

David, thanks for posting that website. There's all kinds of education in that area. All I need now is to find a mentor for a little while, and I'm going to go into business. I don't have much to lose in giving it a go. I'd rather be happy and broke that unhappy with money. Sorry....I was referring to LennyD's site posting. My brain don't always work so good. Too many fumes?

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Hold on. SWAT's at my door.

I don't know how I missed this post earlier but thanks for the response. Yes I meant if the spring is allowed to drive the trigger foward rapidly. I was working the mechanics without the trigger spring installed which is probably why I described it in the confusing way that I did. It isn't a problem of the of the trigger not returning fully. It is the oposite in that the trigger returns too far which makes the sear drop past the notch where it is supposed to rest if the trigger is released too quickly. This is why, if the trigger is released slowly, the sear will drop into the place. The spring might be weak but I actually think it has enough tension, it seems typical compared to all the other revolvers I have opened up. It could be a little soft but not enough to notice, I've seen softer. This is why I was thinking that I could shave off a bit from the sear so that at the point where the trigger is fully in the foward position, the sear could not pass the notch. OR I could weld a piece of metal to the front of the trigger which would prevent it from traveling all the way foward but it doesn't sound like anyone likes this idea.

I just found this article which seems pretty goods. Here it is if anyone is interested...

Case Hardening with Kasenit

What it meant is that, as was posted previously, it isn't a job for a beginner and the fact that you asked the question suggested as much-mainly that you were a beginner in that type of work. Ditto for your statement regarding filling a hammer or sear as opposed to stoning. You mentioned that the gun was an antique which suggests that availability of original replacements parts in the event of a DIY oops might be problematical.

Bruce

I used kasenit quite alot in high school more decades ago than I care to admit. It works great. It will even put some "color" in the hardened part. My understanding is that the case hardening brand Kasenite is on a very restricted distribution list because of the nasty chemicals found within. It may be totally banned. I couldn't find any in the US but there were some places in Canada that still had it.

Brownells used to sell Kasenit, but now as you see they sell something else. I have no experience with the new stuff so I can't speak to how well it works. There are formulas that can be found online that reveal the chemistry of case hardening compound and apparently you can make it yourself. In any event, if you fit your parts before you harden them then the hardening would only need to be a couple thousanths deep.

BTW, I believe there may be propane or butane torches that will bring low carbon steel up to critical temperature so you don't need an oxy/acteylene torch unless you already have one.

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Dixie Gun Works has Kasenit:
Dixie Gun Works muzzleloading, blackpowder and rare antique gun supplies.

I'm skeptical about case hardening at home. Case hardening can takes hours at temperatures exceeding 900*C (it has to be hot enough to change iron's crystal structure). Its time is variable depending on temperature, depth of treatment, and the desired carbon content. Higher temp and shallower depth = less time but it still maybe quite a while at a high temp. It's governed by Fick's 2nd law, and you can calculate the time needed with additional info which can be found if you really want to. I imagine it will be VERY thin with a DIY method.

DIY case hardening at home is possible. I did it successfully back in the 80s. Perhaps I just got really lucky, but I do believe I could succeed again.

Now, I don't doubt it was very thin. However, it seemed to work. That particuliar revolver functioned just fine for a long time.

I can't guarantee any success. Lots of variables that can trip you up. But, it has been done successfully at least once.

If you try to fix a part that you know is bad at the very least all you will wind up with is a part that's bad. Go for it that is how things get fixed.There is no black magic in gunsmithing!!!!!!!!

Ok, this is the first it's been mentioned that the trigger may overtravel if released quickly. I was trying to get a handle on how the sear/hammer interacted or I might have wondered about it.

The IJ type revolvers weren't really intended for heavy use, so some wear that allows the behavior you mention could be reasonably be expected. A stop to limit forward travel would definately work. Just looking at the parts, it would seem that the forward edge of the trigger guard cutout is supposed to act as the trigger stop. A bit of wear or missing the dimensional tolerances slightly might cause the issue over time.

Perfect, thanks for the link!