doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com hardning sear

Soft sear older hammer gun.Would heat to 1472F (electric,computer kiln) for 5 min and quench in quenching oil;then temper to 580F for 1.5 hour and then allow slow cooling work? Of course unknown steel composition.

Couple of points. The sear may be low carbon steel and not harden at all or it may be plain medium carbon steel and will harden. If it will harden at all, you probably should quench in water. There will be no benefit to holding it at temper temperature longer than needed for it to heat all the way through. If it doesn't harden, then you will want to case harden it - Kasnit is a common hardening medium.

DDA

I used Kasenit years ago on the sears of a Billinghurst type underhammer pistol I built. I also used it a couple times to case harden nuts that I drilled reliefs in to make thread chasing dies. Hard N Tuff and Cherry Red are other brands of surface hardening compounds. Once I used regular table sugar as a surface hardening compound to make an emergency thread chasing die, and that worked too for the single job I used it on.

Check to see if the sear is case hardened or through hardened.

If soft steel under a couple .000" of glass hard surface anywhere on it,,re-case harden.
I use Kasenite for years and it works fine. I'm sure the other products do to.

If they're through hardened,,and you don't know what type of steel in this instance,,water or oil hardening. Quench in water with a slick of oil on the top of the water.
It'll in most every instance harden the steel so you don't have to repeat the operation if you choose the wrong medium.

I'd anneal them first and do any rework on them necessary (or not).
Wether the annealing is or is not advantageous to the re-hardening/tempering that's to follow is for the real experts to say. I always figured it was and did it that way.

Temps sound OK to me as we're just guessing at what the stuff is anyway. I'd draw them so that a new, fine cut file would just barely cut the sear.
Having the kiln sure helps.
No need to prolong the tempering heat soak.

Bill
My WAG is that 450-470F is probably as high as I would temper. I used this temper on a Colt Python hand that I made about 30 yrs ago. It lasted for years until the gun was sold.

Hope it works out. Seem like it would be tough to arrive a specific times and temps without knowing your steel. Maybe the part has been around a while and doesn't need hardening. Main thing I'd wonder about is altering the sear due to heating it exposed to oxygen and possible warping.

If you know the steel, depending how you do it, 5 minutes in an electric kiln may not bring the whole part up to uniform temp. It's true that many heat treat recipes call for longer tempering times, but as mentioned it may not have the ability to harden in the first place.