Case Hardening Always Needed After Sear Stoning?

[Louca]

I have polished a few AR trigger and hammer sears, but I wonder if I should have followed that up with case hardening. Does stoning and other polishing remove any surface hardening? Sometimes I use 600 grit sandpaper followed by crocus cloth; sometimes I use a stone then crocus cloth; sometimes just crocus cloth.

I see Brownells sells Surface Hardening Compound and I was thinking maybe I should use that.

Years ago, I polished the trigger sear on my Colt 1911 and it works fine now 30+ years and thousands of rounds later. So should I be concerned about having soft surfaces now that I have polished them? Thanks.

Lou

 

[BBBBill]

Standard AR-15 hammers and sears have very thin hardened skins. It is very easy to cut through that to the softer inner metal. Not recommended. Better to spend the money for a quality aftermarket set like Geissele, Wilson, Timeney, etc.

 

[rcmodel]

I don't know.

The 1911 sears you worked on were hard clear through.
So you simply couldn't polish or stone through it to the soft interior.


But, AR trigger parts are only surface hardened, and you Can easily cut through that.

Then, as to case hardening the parts???
The problem is 'Only The Shadow Knows' what kind of 'Mystery Metal' every company making AR triggers are making them out of?

So who knows for sure what needs to be done to re-harden them without making them softer, or too hard & brittle?

Conventional wisdom as far as I know is, don't stone them.
If you need a better AR trigger that will be safe, and stay safe forever?

Buy one thats already better.

rc

 

[BBBBill]

I read somewhere that the hammers and triggers were sintered. Do not know the truth of that or whether it has changed over the years.

 

[rcmodel]

+1

Unless they are high-dollar forged & machined parts?
They very likely are sintered, cast, or otherwise, the 'Mystery Metal' I mentioned.
If they are forged & milled parts?
They would't need a trigger job!

Don't risk trying to case harden something you have no idea whether is good high grade steel that will respond well to case hardening, or not.

rc

 

[Louca]

Thanks guys, good advice. Expensive advice, but good advice.

Lou

 

[Drail]

If you stone more than a few thous. off I would expect it to wear pretty fast. I would go ahead and order a new one.