Morning fella's,

I have recently aquired a Star pistol, circa late 40's. It has been enjoyable and educational learning to handload for the now obsolete 9mm largo, which is sort of a 9mm magnum.

Unforunately the safety on these fine Spanish military pistols was not made of hardened steel, and the surface where it rides on the cam of the hammer erodes over a period of time/use. I have searched around on the web and found some intersting information on "case hardening" small gun parts, but the process is not all that appropriate for the home hobby smith. I have an oxy/acetylene welding/cutting outfit and think that there may be a simple method of hardening this small part, but am very unsure of the details of the process. (how hot? dull red? straw yellow? quench w/water? quench w/oil? don't quench at all?) Please bear in mind that this part must NOT become brittle, as, well, it's a safety.

Any tips appreciated. Thanks!
Clayman

Heat treating requires (usually) knowing the chemical composition of the material you're hardening. If it contains less than .35% carbon you cannot (normally) harden it unless you infuse carbon into the surface of the steel...this is called case hardening and there's several ways todo it.....but probably not at home!!!

You can try to heat the part (cherry red) and fast quench in water. after doing that polish the part with light emery cloth to expose bright steel and then slowly reheat until you see blue colors in the brightened steel and immediately upon seeing the dark blue color you can quench it again in water.

Other quench mediums include oil and in some cases sub zero temp. brine. There again knowing the chemical composition of the material you're working with is the dictator.

Personally.....if it were mine, I'd send it to a commercial heat treator and ask to have it sent thru a cycle with a batch of parts needing .015 deep case hardening......and hope for a favor. Minimum charges usually prevail and run $75

Be your own judge....but be forewarned that you may not be able to do this alone at home.

Years ago some gunsmiths scraped bone and horn and pieces of leather into a pipe . They added the parts they wanted top harden and put caps on each end and put them in the forge for many hours. The bone, horn and leather pieces were high in carbon and in the furnace some of the carbon diffused into the metal parts. Hours later (eight possibly) they was removed from the forge, the baked on soot was brushed and scraped away and the metal parts were then heated, quenched, and then tempered as I initially described.

You can try that too!!!

Best of luck!

I would look into hard chrome plating, if it still works but is just worn. Hardening is going to require heat no matter how you go about it, and that is going to change this part either dimensionally or through warpage. The other option is to use a tiny tiny tip and weld it up again, then file or dremel it back down to the proper size, but man I do not like to use heat on small stuff.

However, if you want to try something use Kasenit, it is a powder that you heat the part up bright red then dunk it into the stuff. Repeat, and heat once more then dunk in water. Don't go too bright, and you can use a propane torch for it if you don't have the proper tip.

Mark is right , Kasenit is used by gunsmiths often.For small parts you can use propane . It has to be heated to red ,~1500F, held at temperature a minute or two and quenched .This will produce a hard case on the part. Find it at www.brownells.com

On a small mild steel part it is possible to harden it by introducing carbon into the surface with a carburizing flame with your oxy/acet torch. Adjust the flame so that it is well short on oxy then heat the part with this flame. It works best if you take the part up almost to a welding heat. To where the surface almost starts to look "wet". At this point you can almost paint the carbon into the material. For a light part like that you will then reheat- again, using your carburizing flame- to roughly 1500 degrees then quench in cool oil. Check hardness with a file. Since you are primarily concerned about a wear surface, you will have concentrated your effort on that portion which you want to harden. Holding it with a crappy pair of smooth jawed pliers will help. The pliers will act as a heat sink. You can hold the part behing that portion which you are wanting to harden and limit the heating to that area. Treated this way, the wear surface will be damn hard and will wear well. Regards, Bill

I suggest getting a small container of Kasenit or "Cherry Red" and follow the directions on the container. IF it happens to be a steel with more than .40% C it may through harden. So, after completing the heat treat as directed I would take it up to about 425 deg. F. for a few minutes. That can be done with a torch, go slow and seek a light straw color. You can put it on a pc. of sheetmetal and heat from below, go slow, no hurry.

If it is mild steel and will not harden by heating and quenching, use Kasenite.

To tell what you got, heat to red heat and quench. Check it for hardness by trying to cut it with a file. If it is to hard to cut, the steel is heat treatable. Now that you have it hard you need to draw it, otherwise it will be too brittle and will break in service. I would draw it to a dark straw or purple color, if you go the open air route. Better to use a lead bath, read that as bullet casting pot, it will heat it evenly. Let it soak for several minuets at the proper temperature. Hold it under the surface by wrapping a piece of wire around it. Heat to 700 deg. F., if you have a thermometer. Quench in oil. If it were spring stock it woud be springy and tough, that works for me. If tool steel you have a good compromise.

I have used Kasenite to harden lock parts for muzzleloaders.

The procedure is as has been posted , heat,dip in kasinite, heat again, (the Kasenite powder will melt onto the surface) dip in kasinite again, heat then quench. Yes a propane torch will work just fine for small parts.

I even do the heads of the screws that hold the tang and lock in the stocck. The repeated asseembly/disassembly causes the slots to get mangled, a little kasenite prevents that.

Absolutely great information from all of you. Thanks so much. It will save me much time and headache. I have a couple of extra thumb safetys from Sarco, they are only a couple of bucks, so I can afford to experiment with some of the suggestions you all have offered. I probably won't get back to this project untill after Christmas, and if anybody is interested, will report on the results.

Thanks again,
Clayman

I make from scratch a hammer for an old .32 rimfire bicycle gun for my barber. I used the heat to cherry red, quench in water, polish, heat to light straw, quench and polish route. It worked perfectly and only took a total of 15 minutes using a dremel.

I set the part on a steel plate to help keep the heat even. Use quick light wiping motions with a propane torch and stop one or two wipes before you think you should. The color comes on real fast and it's easy to go too far.