AR Sponsor
Posted: 5/3/2008 7:21:58 PM EDT
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Get Bill Springfield to do a trigger job on it. He does a great job at a reasonable price. [email protected] |
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The problem with working on a stock AR trigger is that the hardening is notoriously thin. Very easy to stone your way into the chewy center and end up with a trigger that passes function test at first but will fail before to long. There used to be sticky about the "fifteen minute trigger job" or something like that. |
OK, so given that the hardening is thin. Is there any reason not to stone it till it's good then reharden it? Use a torch till it's a nice straw color then quench in water? |
Once you get below the "case hardened" layer, the base metal WILL NOT respond (as in harden) to just reheating and quenching. It's the carbon or nitrogen infused into the metal that results in the hardened surface.And depending on which process was used that layer may be only a few 10,000 of an inch deep. |
Wouldn't the heating break down the carbon/nitrogen? How do you re-harden it then? just curious. |
Wrong...these parts are not "case hardened"...they are "heat treated" and therefore are hard all the way through. You can tell because after they are heat treated, they are ground on a precision surface grinder that gives those shiny mating surfaces. You shouldn't have a problem with stoning it. Even if it was case hardened, that will get you a "case" of up to .006, not .0003. Also, I would not cut my springs, as suggested by the 15 minute trigger job. I would buy some JP underpower springs and go from there. Good luck, -Jbot |
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Taken from the wiki page on case hardening... "typical depth of surface hardening with this method is up to 1.5 mm" 1.5 mm = .059 inches. A few 10,000's is .0003. Big difference. Besides, old guns such as the Colt SAA have case hardened parts, as they are made of low carbon steel and also exhibit that case hardened look of "fire" on the surface of the steel. The steel parts in a modern ar (or most modern firearms, for that matter) are high carbon and are therefore heat treatable. -Jbot |
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You guys need to work with me, just a little, I'm pushing 70 and just built my first AR last week. Some times I need to hear something more than once. Since the trigger is heat treated a little smoothing with a stone should not cause any problems, unless the contour is changed. If the trigger was case hardned a little smoothing with a stone could wear the hardned layer away. Am I correct??????? |
Yes, you are correct. Your ar trigger/hammer is heat treated. And it's possible to ruin a case hardened part, though, in all likelyhood, a little stoning is not going to go all the way through a case hardened part, as "stoning" is used to remove burrs and will not remove more than a couple of "tenths" (machinist talk for .0001"). If you are removing more than that, you are not "stoning". -Jbot |
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