doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com a little over my head

Hello there,

I'm bunker shooter for about 5years, after using different guns I settled on Perazzi MX8, and last year I bought Beretta SO5 and we really like each other
But the problem from the very beginning was a very light bottom trigger ~1.8lb, that results in premature, you know what.., costing me lost targets every time I go to the range. I stopped shooting the gun as it becomes a hazard.
Eventually I modified the set of gunsmith screwdrivers and opened the side locks to find that the sear is rounded with signs of someone working on it.

I always worked on my guns successfully (most of the time ;)), but this is different, and I'm approaching it very carefully, not to screw it up.
I decided to to tackle it myself, as only gunsmith I would take it to has a shop in the other world, and not going to ship it to US.
I bought a Power Custom Sanding Fixture II in the US with attachments I have to modify to fit the sear with help of a CNC operator friend, project challenging in itself.
Bought a set of diemaker stones grits from 100 to 1200. Have stereo microscope with digital camera that is calibrated, with software enabling me to see it and measure on a computer screen with .001mm accuracy.
Sears engagement with hammer is ~.5mm at 87deg angle (top barrel, trigger pull ~2.3lb), my goal is to have trigger pull ~3lb, as is on my Perazzi.
Given that I'm successful in achieving it, there is a a problem that I have to tackle, but not sure how.
I know I need to harden the sear's tip that I'll stone, I have an access to the nitriding process and other case hardening methods, but I don't think it's a good idea to do it to the whole piece, I'm reading about how to, but would really appreciate a targeted advise.
I'm not sure it would be possible to find what steel/alloy the sear is made of, and I assume it's a proprietary secret, the only thig I could do it to measure HCR =43.7 , of the body, surprisingly soft , comparing to trigger group on other guns I checked before.

TIA,

Kaz

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 a metal container with 5W-20 oil in it until the oil is about 450 degrees F and drop the hardened sear in the oil and that will temper it just fine. 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