Is my sear wearing out?

[DOHCTR]

Hello gentlemen,

I was cleaning my FNC the other day and noticed that the sear seems to be wearing a bit. This conversion was done by Todd at TBA Suppressors and I have shot maybe 1,000 rounds through it. Should I be worried about this or is this kind of natural wear and tear? The metal is not chipping off, but rather compressing into itself:

Thank you in advance!

 

[okpud]

Just my guess, but it looks like it wasn't hardened, or hardened properly. The sear is just stamp cut 4130 (or very similar) steel. Your sear shouldn't look like that after only 1000 rounds. Not a big deal, as you can also have it welded to fill it in if it gives you problems, but it probably should be hardened via heat treatment.

"Heating at 1600 F followed by an oil quench will harden the 4130 alloy. For best results a normalizing pre-hardening heat treatment may be used at 1650 to 1700 F followed by the 1600 F soak and oil quench."

 

[DOHCTR]

Thank you okpud. I can always repair it by hitting it with a bead and filing it down flush so I am not too worried about being out a few grand, but I am worried that it may have an out of battery detonation or something.

I have a spare FNC sear in my safe that I may send off for proper hardening though in the mean time.

 

[xm15e2s]

There is a reason people go to S&H for conversions.

I wonder if S&H heat treat the sear after they shape it for their conversion?

I dont recall mine wearing like that.

 

[XxLT250RxX]

There is a reason people go to S&H for conversions.

I wonder if S&H heat treat the sear after they shape it for their conversion?

I dont recall mine wearing like that.

+1 on the S&H conversions. I's hard to go wrong with the one who invented it. I was told (not by S&H) that he does. A phone call to Curtis and we would know for sure.

 

[DOHCTR]

+1 on the S&H conversions. I's hard to go wrong with the one who invented it. I was told (not by S&H) that he does. A phone call to Curtis and we would know for sure.

Thank you for the input guys, much appreciated. I will call Todd to see if he will take a look at it.

Also, Curtis Higgins did not invent the FNC Sporter to full auto conversion. Bill Fleming did, but Curtis did the registered sear thing while Bill did receiver conversions.

 

[XxLT250RxX]

You are correct of course. Since we were talking about your registered sear I assumed everyone knew my comments were directed at the registered sear conversion and their maker Curtis Higgins.

 

[DOHCTR]

You are correct of course. Since we were talking about your registered sear I assumed everyone knew my comments were directed at the registered sear conversion and their maker Curtis Higgins.

Yes indeed.

I have met Bill and talked for him for a while and he is a stand up guy, but I have not met Curtis before. Funny how their shops are so close. Bill did of course speak well of Curtis.

 

[okpud]

When I did my own conversion, I heat treated my sear because it seemed on the soft side to me. I don't know how many thousands of rounds I have on the sear, but it has no noticeable wear on it. I think by the end, S&H was cranking them out as fast as they could and slapping a serial number on them to get them done before the May 1985 deadline. I doubt they were spending a few hours a batch heat treating them.

 

[DOHCTR]

That sounds very plausible okpud, I can only imagine how hectic things were at his shop when they were filling out form 2s and electro-penciling on serial numbers!

 

[DOHCTR]

delete

 

[deadduck]

Hey DOHCTR -

Wrong thread for that response.

Here you go. http://www.uzitalk.com/forums/showthread.php?74034-The-New-FNC

 

[DOHCTR]

doh!

 

[Gracie]

From the second of a two part article on the FNC which was written by someone who toured Curtis Higgin's shop in late 1998 or early 1999:

To quote part of a paragraph in the second article "The sear itself has a Rockwell hardness in the mid 40s and is made of 4130 steel which has been precisely machined and hardened via an oil quenching. Paragraph concludes "Further, he has never had a sear fail or wear out."