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Thread: Hardening

  1. #1
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    Hardening

    I made a new firing pin for a friend out of a piece of drill rod and am wondering if I need to harden it in some way. If so can someone give me the info on a simple hardening process. Thanks.

  2. #2
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    Drill rod is made in three common grades.Oil hardening,water hardening and air hardening.
    Which do you have?

  3. #3
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    if it was a govt project it is most likely oil hardening if it came from a vendor like fastenal or somebody that stocks industrial shops. it needs to be made oversize, hardened then ground to size since any of the homemade heat treats on a drill rod will change the shape and size and it will be scaled with carbon afterwards. what gun was it for since buying one will most likely yield the easiest and cheapest end result

  4. #4
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    Quote Originally Posted by runningbear View Post
    I made a new firing pin for a friend out of a piece of drill rod and am wondering if I need to harden it in some way. If so can someone give me the info on a simple hardening process. Thanks.
    Sure,

    Slowly heat it to a gentle cherry red and quench it in water.

    Now polish it off silver again and reapply the heat until it turns back to a light brown verging on copper, the entire pin and shank......leave the bearing surfaces hard. Now, we don't know what you've got so let me add that you should "draw back" any areas which are taking impact. The initially hardened drill rod is very brittle, prone to shattering. Drawing it back or annealing it with reapplication of heat normalizes it and toughens it, keeps it from shattering. Draw back to more ductile/less brittle by keeping the heat on through copper and into a light blue, re-quench in water.

    Of course this will only work for simple carbon steels like drill rod.

    al

  5. #5
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    Queensland Australia
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    hardening & tempering

    Touchy stuff if you dont know exactly which steel you have.
    My experience with using scrap carbon steels for tool making in the the forge tells me that your temper is trial and error. In other words temper to what colour you think may work for your purpose ie, straw for still pretty hard or down through the blues for a bit softer. Try it and see if its good, that is, holds its edge or doesnt burr if good leave it, and if not do it again either harder or softer .
    NOW THIS DRILL ROD, if you did not anneal it before machining, or over heat it during machining, it will remain at it's original state of hardness, and if that would be good for the job, well mate you are laughing.
    Simple hardening, from old blacksmiths. Urine. Piss in tin, heat only low carbon or no carbon steel to cherry red, quench in tin.= a sort of case hardening. I have used this method for ignitor trips on low tension ignition antique stationary engines. Please note, this does not apply to your drill rod.
    Back to firing pins, I have made them for shot guns, out of high tensile bolts left at the same hardness, and not a problem ., Hope this helps.

  6. #6
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    Hardening

    Thanks for the input guys. The drill rod I have came from MSC so I would assume it is oil hardened. The pin is for a very old Savage model 24 over and under. Can't find a used one out there and Savage doesn't make the part anymore.

  7. #7
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    Feb 2003
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    If you do not know which drill rod you have, take a couple short pieces of the remaining material and heat treat them. Heat them somewhat slowly until they are non-magnetic and quench at that time. I'd try one in warm oil and another in brine, water with salt added. Urine would be o.k., I guess, if one did not have water and salt nearby but I've never had to resort to that quench medium. Carbon steels become non-magnetic when they reach the critical temperature, a handy feature when flame hardening small parts.
    If the one quenched in oil is hard (try filing it with an old file) then that would probably be a good choice for the firing pin. If not, try filing the piece quenched in brine. If it is also soft, you have a steel w/o adequate carbon to be heat treated in the this manner.
    Try to heat the part evenly and quench straight down into the medium, don't just toss it into a bucket of oil or water. Draw it back as Al suggested and it should be fine.
    MSC (?) has an "anti-scaling" compound that is really great to prevent surface scaling and de-carbing. I've used it for years, also use real quenching oil but forget the souce.
    Personally, I'd get a piece of pre-hard 4140 or similar material and make the firing pin from that.

  8. #8
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    Tennessee
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    Leave it as is.

    If you've already made the part, I suggest you use it as is. It'll take a lot of shooting with a single shot shotgun to wear it out. I think the chance of making it brittle is worse than leaving it alone.

  9. #9
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    Quote Originally Posted by runningbear View Post
    Thanks for the input guys. The drill rod I have came from MSC so I would assume it is oil hardened. The pin is for a very old Savage model 24 over and under. Can't find a used one out there and Savage doesn't make the part anymore.
    You only need to harden the big end that the hammer hits. Then draw it a bit more than brown... to a purple or blue. If you don't harden the whole pin it probably will not break and will last forever. It would not surprise me if you did not need to harden it at all.

  10. #10
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    Aug 2004
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    I'm also not a fan of heat treating firing pins "most of the time". Depends a bit on the gun, but most break open guns are served quite well with a pin made from an annealed piece of drill rod. This material is harder and tougher than many gun steels even in it's annealed state. Just polish it up and remove the stress risers (sharp corners) and you are good to go.

    If you make the head too hard, the next piece you will be replacing is the hammer (a more expensive piece). Trying to differentially harden and temper a piece of high carbon steel usually leads to breakage by shock at the junction of hard and soft portions of the pin sometime down the road.

    Actually, a good firing pin can be made from low carbon steel if no drill rod is available. Just form the pin and case harden using Kasenite. No tempering is required, however note my comment about potential damage to the hammer on some guns.

    Scott

  11. #11
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    Feb 2003
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    Quote Originally Posted by runningbear View Post
    Thanks for the input guys. The drill rod I have came from MSC so I would assume it is oil hardened. The pin is for a very old Savage model 24 over and under. Can't find a used one out there and Savage doesn't make the part anymore.
    Brownells shows them in-stock, items 13 and 14;

    http://www.brownells.com/aspx/ns/Sch...px?schemid=321

  12. #12
    Join Date
    Jul 2004
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    965

    Also, you can try........

    remembering, as has been said, that using too hard a pin, can possibly wear the receiver where the pin bears while operating. Try Steve Simons, at the Small Arms Shop, 813-398-1696 Savage parts, may have what you need. Good Luck

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