• Watch Out for Scammers!

    We've now added a color code for all accounts. Orange accounts are new members, Blue are full members, and Green are Supporters. If you get a message about a sale from an orange account, make sure you pay attention before sending any money!

Gunsmithing 700 bolt lugs , weld and refit to action ?

kcsmith

Supporter
Supporter
Full Member
Minuteman
Aug 9, 2020
150
107
NH
Id like to know if anyone has welded up some bolt lugs and refit them to an action? The play between the lug dimensions and raceway dimensions has me wondering if those tolerances were tighter, would the bolt be less prone to binding. If you have, was it worth it and what type of weld? Laser, tig ?
 
Are you asking if someone has added some hard surfacing welding rod and reground the lugs?
Do you feel like the lugs have worn down some how or just loose factory tolerances.
More info would help you get a better answere. Photos would be nice too.
 
KCSMITH....

You may add some arrows and notes to your photo as shown below.

Years on the computer doing design work, I still have never learned how to use the functions that allow you to add arrows and circles
and notes on the face of an image. Below are post it pieces stuck to my screen. It's crude but it works.
I would appreciate any help I could get from the forum members to use the proper functions. My thing was CATIA V5.....
 

Attachments

  • 6 PIVOT POINTS.jpg
    6 PIVOT POINTS.jpg
    825.9 KB · Views: 174
These two surfaces in particular.
 

Attachments

  • Screenshot_20220504-090257_Gallery.jpg
    Screenshot_20220504-090257_Gallery.jpg
    192.6 KB · Views: 169
Id like to know if anyone has welded up some bolt lugs and refit them to an action? The play between the lug dimensions and raceway dimensions has me wondering if those tolerances were tighter, would the bolt be less prone to binding. If you have, was it worth it and what type of weld? Laser, tig ?

There is so much wrong with this..............welding on a major load bearing portion of the assembly, no understanding of the differences between tolerances and clearances.......wow.

If you want something with closer clearances, buy something else.
 
Good question.

No, the area on the bolt being welded or tightened up will NOT have the desired effect, it will make it worse, to some degree.
 
I dont think this a good idea and as others have stated it'll probably just make it worse.

Out of curiosity, if anyone knows, what are the bolt bodies made of ?
Are they hardened, heat treated ?
 
  • Like
Reactions: Fig
There is so much wrong with this..............welding on a major load bearing portion of the assembly, no understanding of the differences between tolerances and clearances.......wow.

If you want something with closer clearances, buy something else.
Absolutely correct 308pirate...! Plus, one part wearing against another part creates wear on both parts. So you can't expect to fix just one of the parts and solve the issue.
 
I dont think this a good idea and as others have stated it'll probably just make it worse.

Out of curiosity, if anyone knows, what are the bolt bodies made of ?
Are they hardened, heat treated ?
The bolt head and body are 2 seperate pieces, press fit and braze welded together. Head is hardened, bolt body unsure.

I can ping one tomorrow on the hardness tester and see whats what.
 
Personally, I'd give the bolt a light oil coating and learn how to push the bolt handle straight forward and pull straight back.

You can manipulate the bolt very quickly without manhandling it.
In fact, it's faster without trying to rip it off or break the bolt stop.
 
I weld high carbon 4100 series on a regular basis and I strongly suggest you look in a different direction. It can be done but you would have to anneal the bolt head, weld, heat treat, and then temper. The problem with this is knowing the exact chemistry of the bolt head before you begin, otherwise one would be guessing at temperatures/processes to use.

As others have said before, the juice isn't worth the squeeze on this project.
 
Personally, I'd give the bolt a light oil coating and learn how to push the bolt handle straight forward and pull straight back.

You can manipulate the bolt very quickly without manhandling it.
In fact, it's faster without trying to rip it off or break the bolt stop.
But there has to be something wrong with it, because well you know, reasons and stuff.
 
I weld high carbon 4100 series on a regular basis and I strongly suggest you look in a different direction. It can be done but you would have to anneal the bolt head, weld, heat treat, and then temper. The problem with this is knowing the exact chemistry of the bolt head before you begin, otherwise one would be guessing at temperatures/processes to use.

As others have said before, the juice isn't worth the squeeze on this project.

Yeah this is absolutely not a job for an amateur and many professionals won't do it either because of so many metallurgical unknowns.
 
  • Like
Reactions: HiDesertELR
Bolt bind...

Do you have any sand accumulation in the action? During OIF 1 I had to take a dental pick to the action on my M-24 to get compacted sand out as my bolt was sticking. We were doing quite a bit of shooting and the sand was working its way into the action and getting crushed and packing all the crevices in the action where the bolt head operates.

Also, what bolt lube do you use if any? You may have a galling issue.
 
@kcsmith It's not really the bolt lugs that you want to mess with (other than truing). What you want to look up is Remington 700 bolt sleeve modification or 700 double sleeve body.
 
kcsmith,

I'm not familiar with your bolt so I'm going to use mine from a Springfield MK2. Mine is from 1935 and has a "B" suffix.
If you look at the bolt the first thing you will notice is that there is almost no witness marks from rubbing against adjacent
surfaces. I would estimate the bolt shaft itself has less than .005" clearance. The clearance to lug number two varies between
.010" and .025". The only high force and high wear area would be on the back of the lug with a red dot on it. That position
has a hardened round plug installed to rub against the cam area in the receiver that drives the bolt forward upon CW rotation
of the bolt handle.

I would guess that your bolt is correct with the design clearances it has. Many of my bolts are fairly loose until they reach a critical
position that is likely in the final 1/8" of it's forward most position. At it's full forward position, the bolt is locked up tight
and true.

Images 7 and 8 are of an Olympic FWB P70 HP FT air rifle. The sliding breach block that has the air transfer port is pretty sloppy
when in the open position. When it is closed the transfer port needs to be lined up and the breach needs to seal against the barrel
in front and a seal under the breach block to allow air to flow. It can't be loose because 1500 psi of air needs drive the pellet out.
It is only when the breach is fully closed and the male and female cone align that allow this design to work at all.
It's a good illustration of a loose design that tightens up when it needs to.

I doubt the SURFACES you pointed out see any load to speak of. If it were 1922, they wouldn't. Those appear to be upper and
side surfaces not an axial surface that see's any thrust load.

To answere your welding question, since TIG is readily available as is hard surfacing / hard facing rod, that is what I would use
if I were personally doing it.

It sounds like when you say" Binding" , you mean as you cycle the bolt forward and aft the bolt is getting a little off axis. If that
is the case, I don't think any kind of lug work would reduce that.

FYI... There is a process called "Spray welding" that is used to build up the surfaces of worn shafting and other parts. The part is generally
spun and welding material is sprayed onto it. A secondary grinding operation is required to bring it back into the design dimension.
Still nothing that will help your case. About 1980, I had seen an apple that had been spray welded. Why? I don't know... why did they twist the
barrel on the FWB 65 pistol below. 5 or 6 of them actually. I like the last image best for thermal spray welding. A crank shaft is undersized
for some reason and they are building it up to salvage it. In that case they are using a plasma heat source.

On my 1922 shown in the third image labeled 2.jpg, it wouldn't make any difference in function if the surface was ground down by .06"
You can see that the surface with the green dot has ZERO wear on it because it clears by at least .010"alreay.

btw... 308 is correct, there is a differences between tolerances and clearances but he need not be such a flaming Nimrod about it.

I excuse it because it's semantics. The average guy on this forum doesn't know or even need to know the difference. Your query
was perfectly clear to me. TIGHTEN THINGS UP WITH WELD.

Your question about laser or TIG is really about the best process to use. He wont do it himself or he would not be asking the question.
If it is electron beam welding, that is all he wants to hear. The best process.

I have manually welded SS with TIG. ( GTAW ) The weld was a fillet fusion and the weld size being about .040" and very little HAZ. I would have
little concern about adding some hard facing to a surface and then have it sent out to be reground. Do I still weld for a living? No!
I was able to do the welds because I had surface ground every surface of the 3/8" thick SS prior to welding. My welds were very straight
and glassy smooth with no weave. The ones below are very nice... mine had a very different texture. The last thing I welded was 4130
air foil profile tube for landing gear. I used some local welding rod and the results were imperfect. I think that was about $3.00 a pound.
I decided to get some MC grade rod from Lancaster Alloys in CA. As I recall it was $30.00 a pound and free of the copper coating found on
most filler rod. The welds became perfect !! The welds were in plain sight and my name was going to be attached to them forever.
That must have been in 2002.

Because it was surface ground, there was virtually no gap to fill and no filler rod to add. I kept the assembly true and square with 1x2x3 blocks and
because of my tack placement, I was able to remove the 1x2x3 block without putting a single scratch on the ground surface's and then
put it back in place. I had to stop and start a few times but it was undetectable. All of my welds and HAZ had very pretty colors like
the weld below. It wasn't a structural piece... it was basically a desk top trophy that would hold a small plaque and a mechanical
pencil that Tony had used for about 40 years while at the company.

When I went to school, brazing and welding were two distinct process's. We would never say "Brazewelding" Brazing is done below the
melting point of the parent metal and welding actually fuses the parent metal with or without filler. If the parent doesn't melt than it isn't welding.
It's brazing, silver soldering..... bonding. That said... a silver soldered joint with a .003" gap has a tensile strength of 50 / 55K psi.


Don't weld your lugs and learn all you can your entire life.
 

Attachments

  • THERMAL SPRAY 2.jpg
    THERMAL SPRAY 2.jpg
    75.6 KB · Views: 69
  • FWB 65 TWIST.jpg
    FWB 65 TWIST.jpg
    7 KB · Views: 60
  • BREACH  LOCATING CONE RECEIVER.jpg
    BREACH LOCATING CONE RECEIVER.jpg
    287 KB · Views: 59
  • BREACH MALE LOCATING CONE (1).jpg
    BREACH MALE LOCATING CONE (1).jpg
    399.7 KB · Views: 48
  • WELD.jpg
    WELD.jpg
    101.2 KB · Views: 49
  • SPRAY WELDING.png
    SPRAY WELDING.png
    1.3 MB · Views: 68
  • 3 AND 4 RED.jpg
    3 AND 4 RED.jpg
    243.2 KB · Views: 77
  • 2.jpg
    2.jpg
    307.8 KB · Views: 76
  • 2 AND 3.jpg
    2 AND 3.jpg
    301.1 KB · Views: 61
  • 1.jpg
    1.jpg
    344.5 KB · Views: 66
Id like to know if anyone has welded up some bolt lugs and refit them to an action? The play between the lug dimensions and raceway dimensions has me wondering if those tolerances were tighter, would the bolt be less prone to binding. If you have, was it worth it and what type of weld? Laser, tig ?
How does the gun shoot? If it shoots, shoot it. If it doesn't, get a new bolt and have it fitted... and keep yo face purdy ;)

Last thing I want to do when behind the rifle is to wonder "is THIS the time the dang thing is going to let loose and put me on a hospital food diet for a few weeks?"
 
To answere your welding question, since TIG is readily available as is hard surfacing / hard facing rod, that is what I would use
if I were personally doing it.

It sounds like when you say" Binding" , you mean as you cycle the bolt forward and aft the bolt is getting a little off axis. If that
is the case, I don't think any kind of lug work would reduce that.

FYI... There is a process called "Spray welding" that is used to build up the surfaces of worn shafting and other parts. The part is generally
spun and welding material is sprayed onto it. A secondary grinding operation is required to bring it back into the design dimension.
Still nothing that will help your case. About 1980, I had seen an apple that had been spray welded. Why? I don't know... why did they twist the
barrel on the FWB 65 pistol below. 5 or 6 of them actually. I like the last image best for thermal spray welding. A crank shaft is undersized
for some reason and they are building it up to salvage it. In that case they are using a plasma heat source.

On my 1922 shown in the third image labeled 2.jpg, it wouldn't make any difference in function if the surface was ground down by .06"
You can see that the surface with the green dot has ZERO wear on it because it clears by at least .010"alreay.

btw... 308 is correct, there is a differences between tolerances and clearances but he need not be such a flaming Nimrod about it.

I excuse it because it's semantics. The average guy on this forum doesn't know or even need to know the difference. Your query
was perfectly clear to me. TIGHTEN THINGS UP WITH WELD.

Your question about laser or TIG is really about the best process to use. He wont do it himself or he would not be asking the question.
If it is electron beam welding, that is all he wants to hear. The best process.

I have manually welded SS with TIG. ( GTAW ) The weld was a fillet fusion and the weld size being about .040" and very little HAZ. I would have
little concern about adding some hard facing to a surface and then have it sent out to be reground. Do I still weld for a living? No!
I was able to do the welds because I had surface ground every surface of the 3/8" thick SS prior to welding. My welds were very straight
and glassy smooth with no weave. The ones below are very nice... mine had a very different texture. The last thing I welded was 4130
air foil profile tube for landing gear. I used some local welding rod and the results were imperfect. I think that was about $3.00 a pound.
I decided to get some MC grade rod from Lancaster Alloys in CA. As I recall it was $30.00 a pound and free of the copper coating found on
most filler rod. The welds became perfect !! The welds were in plain sight and my name was going to be attached to them forever.
That must have been in 2002.

What are you doing about the welding induced metallurgical changes to the bolt lugs, which contain the axial force generated on the breech face by the roughly 60 ksi of chamber pressure?


Crickets............that's what I thought.
 
Last edited:
What are you doing about the welding induced metallurgical changes to the bolt lugs, which contain the axial force generated on the breech face by the roughly 60 ksi of chamber pressure?
That could be simply, easily and safely dealt with by buying a new bolt and having it fitted…..
 
In the blueprinting class we NEVER welded on the bolt lug. As others point out, you're going to compromise the bolt's integrity. When the bolt was coverted from the Rem extractor to a Sako type extractor, the bolt was cut first to remove the rim that retained the Rem extractor and a collar silver soldered in before the bolt was milled for the Sako extractor.

I actually hate doing that conversion but it was part of the class so it was done for the experience.
 
Last edited:
Well duh its a surface weld so if you go real fast it won't heat up the parent metal too much.
No joke, we've had guys come in the shop asking if we can put "cold weld" on something because a hot weld would mess it up... Same people that bring destroyed parts in that were assembled with an interference fit. They would "sweat them apart" with heat and a press, obviously NOT in the correct way.
 
  • Haha
Reactions: 308pirate