The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > The Smithy

Reply
 
Thread Tools Search this Thread
Old March 19, 2021, 04:44 PM   #1
45flaco
Senior Member
 
Join Date: November 19, 2017
Posts: 105
Weld vs solder firing pin

Hey guys. Need to lengthen an ar-10 firing pin by about 3/4" at the back. Was considering welding a bit onto it, or soldering.
Opinions?
I haven't had much luck making firing pins from bar stock, since they're so damn small, so I'd prefer to just weld or solder a bit of bar stock to the back of it.
45flaco is offline  
Old March 19, 2021, 05:23 PM   #2
Bill DeShivs
Senior Member
 
Join Date: April 7, 2006
Posts: 10,663
Solder won't hold up at all.
Hard solder might work.
Welding might burn it up. Why not just get a new firing pin?
__________________
Bill DeShivs, Master Cutler
www.billdeshivs.com
Bill DeShivs is offline  
Old March 19, 2021, 06:05 PM   #3
dahermit
Senior Member
 
Join Date: October 28, 2006
Location: South Central Michigan...near
Posts: 6,341
Quote:
Originally Posted by 45flaco View Post
Hey guys. Need to lengthen an ar-10 firing pin by about 3/4" at the back. Was considering welding a bit onto it, or soldering.
Opinions?
I haven't had much luck making firing pins from bar stock, since they're so damn small, so I'd prefer to just weld or solder a bit of bar stock to the back of it.
Soft Solder: Relatively weak alloy of Tin and Lead. Does not need "Red Heat". Does not hold very well.
Silver Solder: A.K.A. Silver Braze...not to be confused with Soft Solder consisting of Tin and small amount of Silver. Silver Solder is way stronger than Soft Solder. Uses Red Heat.
Braze: Brass based...uses Red Heat.
Welding: Strongest...the base metals are melted and flow together at higher than Red Heat (steel melts at about 2700 degrees F.)
Note: using any method listed can can negatively effect the properties of the steel firing pin.
It would be better if you would give a sketch of the firing pin with dimensions to a machinist/gunsmith and have him make and heat treat the firing pin for you.
dahermit is offline  
Old March 19, 2021, 06:28 PM   #4
HiBC
Senior Member
 
Join Date: November 13, 2006
Posts: 7,478
I don't know the name of the outfit,but there is a business that custom makes AR pattern rifles in 30-06 length and supposedly magnums.

I have zero experience with them.

But I would suppose they don't have a place to buy parts,so they probably make them.

Somebody here on TFL will know who I'm talking about. Is not like your pin would be their first rodeo.They would have proper steel.
I'd guess the pins are turned heat treated and ground. They may be nitrided,and seems like they look hard chromed.

I don't expect you'd turn a good one out of a bridge timber spike.

Thats the best leade I can give you.Be aware,custom stuff costs a lot of money.
HiBC is offline  
Old March 19, 2021, 06:34 PM   #5
4V50 Gary
Staff
 
Join Date: November 2, 1998
Location: Colorado
Posts: 21,164
Low temp, high force solder?
__________________
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!
4V50 Gary is offline  
Old March 19, 2021, 09:13 PM   #6
Bill DeShivs
Senior Member
 
Join Date: April 7, 2006
Posts: 10,663
"Low temp, high force solder?"
Really- these is no such thing.
__________________
Bill DeShivs, Master Cutler
www.billdeshivs.com
Bill DeShivs is offline  
Old March 20, 2021, 10:08 AM   #7
dahermit
Senior Member
 
Join Date: October 28, 2006
Location: South Central Michigan...near
Posts: 6,341
Quote:
Originally Posted by Bill DeShivs View Post
"Low temp, high force solder?"
Really- these is no such thing.
I think that he is referring to one of those Silver bearing soft solders that came out some years ago when Lead based solders were fading from use to to the fear of Lead. They might have had a higher tensile strength than Lead/Tin solders, but were only had a slight improvement in tensile strength.
dahermit is offline  
Old March 20, 2021, 10:42 AM   #8
jcj54
Senior Member
 
Join Date: February 28, 2011
Posts: 137
Best option is make a new pin. Small diameter is challenging, but if you support the smaller end with a live center (making that end sufficiently longer and then facing off after small diameter is made) it is not so bad. Welding firing pins has never worked well for me, always wound up making a new one.
jcj54 is offline  
Old March 20, 2021, 11:35 AM   #9
dakota.potts
Senior Member
 
Join Date: February 25, 2013
Location: Keystone Heights, Florida
Posts: 3,085
If I were going to do it I'd probably turn a shank on the end of your firing pin and then poke a hole in your extension so one slides over the other. Should help with concentricity as well as contact area.

Or if you're going to give a go at making another one - the trick to small diameter parts in my experience is good fixturing, very sharp tools, tool nose depth management, and appropriate feeds and speeds. You want as much energy as possible going into peeling off chips and as little as possible applying pressure to the length of the part. Easier said than done, I know.
__________________
Certified Gunsmith (On Hiatus)
Certified Armorer - H&K and Glock Among Others
You can find my writings at my website, pottsprecision.com.
dakota.potts is offline  
Old March 20, 2021, 12:53 PM   #10
T. O'Heir
Senior Member
 
Join Date: February 13, 2002
Location: Canada
Posts: 12,454
Why do you need to add 3/4"? Mostly just curious.
"...firing pins from bar stock..." Has to be the right steel. Mild steel won't do. The steel has to be tough vs really hard. It gets whacked a lot.
I suspect you'll find any solder is too soft. And weld is too brittle. I'm wondering if welding a wee, tiny, small bit of steel on and grinding it to finished size would do it. You'd still have small size working issues.
dahermit's "red heat" will take any remaining temper/hardening out of the steel too.
__________________
Spelling and grammar count!
T. O'Heir is offline  
Old March 20, 2021, 01:43 PM   #11
jcj54
Senior Member
 
Join Date: February 28, 2011
Posts: 137
Making firing pins

My grandfather, a well known riflesmith active from 1933 to 1972 made firing pins out of water hard tool steel then heated them and quenched them in oil. Did not get very hard but became very tough and wear resistant.
jcj54 is offline  
Old March 21, 2021, 12:55 AM   #12
45flaco
Senior Member
 
Join Date: November 19, 2017
Posts: 105
So, first off, thanks to everyone for the answers. I appreciate it.

I'm thinking that I'm going to do a combination of the answers here. Turn a small shank on the existing pin, and soft solder an extension over that. Shouldn't be too hard.
The reason that I'm trying to do this is because building this rifle has been kind of educational for me, so I'm trying to do all the work myself. I could have someone else do it, but then again I also could have bought a factory rifle and skipped the whole process, lol.
As far as the heat ruining the temper, I'm planning to put the nose of the firing pin down in a brass block, as a heat sink. The back of the extension will get a tiny tack weld, then ground to shape, as basically the world's smallest hardfacing.
Will hopefully be able to update y'all sometime this week.
45flaco is offline  
Old March 22, 2021, 05:41 PM   #13
Bill DeShivs
Senior Member
 
Join Date: April 7, 2006
Posts: 10,663
As I said before- soft solder won't work.
But-since this is a learning experience for you, go ahead. Some people have to pee on the electric fence.....
__________________
Bill DeShivs, Master Cutler
www.billdeshivs.com
Bill DeShivs is offline  
Old March 22, 2021, 05:53 PM   #14
dakota.potts
Senior Member
 
Join Date: February 25, 2013
Location: Keystone Heights, Florida
Posts: 3,085
You're going to want to harden and then temper at least the extension (especially at the rear) and the joint area where the two meet. The last thing you want is any part of your firing pin galling, peening, mushrooming or bending where it's very likely to bind the bolt carrier during travel. To me that says at least 1100 degree solder, over 1400 being preferable, so that it will withstand the heat needed to do so.

Even if done successfully, you're going to have an inherently weak firing pin due to the additional length and two-piece construction. Whether that will manifest over the lifetime of the gun, I can't say one way or the other but it's something to be aware of.
__________________
Certified Gunsmith (On Hiatus)
Certified Armorer - H&K and Glock Among Others
You can find my writings at my website, pottsprecision.com.
dakota.potts is offline  
Old March 23, 2021, 03:51 PM   #15
Scorch
Senior Member
 
Join Date: February 13, 2006
Location: Washington state
Posts: 14,728
Best teel for firing pins is spring steel. Machine it in its hardened/tempered state using carbide tooling. Or use S7 tool steel, machine in its annealed state then have it heat treated. If you weld on a firing pin, it will make it easy to break or deform.

3/4" is a LOT to add to a firing pin. Why? If you need to extend the nose of the firing pin (firing pin broke and is impossible to replace), drill a small, deep hole in the tip and insert a piece of spring steel. I have fixed dozens of firing pins in this manner.

An AR-10 firing pin is only about $15, why go to all the trouble you are talking about?
__________________
Never try to educate someone who resists knowledge at all costs.
But what do I know?
Summit Arms Services
Scorch is offline  
Old March 23, 2021, 04:54 PM   #16
HiBC
Senior Member
 
Join Date: November 13, 2006
Posts: 7,478
I would concur on S-7. H-13 might be another good steel.

I would think if I were manufacturing AR firing pins I'd want them heat treated,ground,and nitrided. That takes capital tooling.The frosty silver look suggests they are hard chromed.

I doubt you'll get what the AR needs using common W-1 or O-1 drill rod and eyeball torch heat treating.

Be aware if something goes wrong and the firing pin binds up you may have a full auto gun with an unlocked breech.
HiBC is offline  
Old March 24, 2021, 08:58 AM   #17
4V50 Gary
Staff
 
Join Date: November 2, 1998
Location: Colorado
Posts: 21,164
If it's a shooter, buy one. We were taught to make firing pins. My suggestion is for historical pieces that you want to keep with all original parts.
__________________
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!
4V50 Gary is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:43 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2020 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Page generated in 0.07534 seconds with 10 queries