Refinishing sear spring
 

Just completing the refinish of a DWM commercial. The sear/trigger bar spring was originally blue. Through the years it has lost most of it's finish. Can I flame blue this without compromising the spring? I understand this spring is very important to a safe weapon and don't want to weaken it.

You can heat it to fire blue it, but then must quench it to retain the spring qualities. You might want to research times and temperatures before proceeding.

Springs are funny things..Like Doug says it might be best to research spring making temps etc. But I think the fire blue temperature is the last of the spring making process...it is the tempering part that will not affect spring tension. It brings the spring from hard brittle to the proper temper.

So..I think if you simply recolor the spring..DO NOT go over the light fire blue with your torch the spring hardness will not change from what it is now.

I tried the fire bluing on the spring. It looks to have worked. Quenched with WD40 as soon as the blue appeared. The change from straw to blue was very quick. The trigger pressure feels the same. I guess range time will tell. Thanks everyone

Yes, the color is from the tempering, and I have done it exactly the way you describe it without problems. As long as you don't go any further than the original color, you should have the same temper as before.