Dear Kaz;
I doubt that your SO5 has exotic or proprietary steel of the sear. Hardening a sear is not difficult, but since it is small it is easy to overheat it. You may want to try hardening a small piece of steel to gain experience.
Heat the sear with a small propane torch until a magnet will no longer stick to it and drop the sear into a container of oil (5W-20 works very well) that has been heated to 100 degree F. After the sear has cools polish it to remove the oxide from the heating. Of course you do not want to polish the tip too much that you just worked to get the trigger pull the way you want. Now you are going to temper (remove some of the hardness) the sear. An experience gunsmith would just take the propane torch and heat the sear until it reaches a dark straw color, but that way of tempering may be a bit too risky for you. Instead you can heat the 5W-20 oil a metal container until the oil is about 450 degrees F and drop the hardened sear in the oil and that will temper it just fine. Let the sear remain in the oil for about one minute. You can go to Harbor Freight and buy a infra red lazer thermometer for less than 20 bucks to gauge the temperature of the oil.
Stephen Howell
Last edited by bushveld; 05/22/26 05:33 AM.
