braze-welded mauser bolt head repair... bad surprise... update, what model of mauser?

louthepou

louthepou

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Here's the kind of surprise which I think falls in the "bad" category when receiving a supposedly great hunting rifle... Is it just me, or that's probably the worst possible place to perform some bronze welding? From what I know about metallurgy (very little), one should not mix high-heat and critical metal components subject to very high pressure...




Not sure if the previous owner knew about it, or if he never noticed...
 
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Nothing surprises me much anymore with suprises in the EE.
I'm almost at the point of viewing things in person to avoid
such Buhbuhizm.
I'd sure ask for a refund.

Last EE purchase caught me with a VarX-II rather than an VarX-III as advertised.
A nice crack in the stock that wasn't suppose to be there.
Vender paid full return postage along with a 100% refund.
I'd deal there again with them being courteous and all.

One never knows.
 
just going by the picture here , see the rust that is forming on the bolt face and inside of the firing pin hole ?
that tells me those areas got very hot at one time .

I don't think i'd cut the bolt up , but I would permanently disable it and find another ( it would make a good bolt for a deactivated rifle .)
 
the portion you need to be concerned about is the back of the locking lugs. Even though I would lean towards replacing the bolt, the bluing on the lugs does not seem discoloured and that suggests to me that the lugs and bolt head were not weakened by the brazing. If you replace the bolt, keep in mind that the new one may or may not head space correctly in your rifle

cheers mooncoon
 
I took a P14 barreled action to a machinist friend of mine to have the barrel tenon cut away from the action ring (barrel wrench wouldn't budge it). When I picked it up there was no metal removed so asked "how did you get it out"...his reply was "it just seemed quicker to heat the ring up and it spun right out"...I have no idea how "hot " he made it so that action still sits unused in a box under the shelf. That was the day I decided that I would own my own lathe at the earliest opportunity.
 
I couldn't do that repair without heating the locking lug beyond what I would consider safe. I would not use the bolt, would replace it.
 
Thanks everyone. My first course of action is to see if the seller will take it back. Along with my boot up where it's deserved. But failing that, I will have to either sell the parts at a loss, or find a bolt and spend too much money for what the end result will be worth. Oh well, sometimes you win, sometimes you loose!

Lou
 
You could save the bolt because the brazing material will melt before the steel will. However, you would have to have a proper weld done to fix the problem in the first place.

Not a welding engineer, but with the heat-affected-zone, I think you would need an annealing process after that weld. I have done a tiny amount work on imparted stresses to metals, and mostly they are nothing in the range of the stresses on a firearm bolt to start with--which is probably why this hasn't blown up on someone already....

Probably cost more to fix it than to get a new one.
 
Probably not a great repair. The brazing might not have gotten it hot enough to change the heat treatment of the bolt. The lugs that hold the bolt in are probably fine. I dont know if I would want to shoot it with hot loads thought. I would bet it would last a lot longer than you think but not worth the risk.
 
tiriaq said:
I couldn't do that repair without heating the locking lug beyond what I would consider safe. I would not use the bolt, would replace it.
Click to expand...

I found myself wondering if the brazing was added electrically because using a torch, I would expect discoloured metal for some distance back. The extent of the heating could be controlled with wet rags or some form of heat sink but it would still extend some distance back from the area with the actual material added

cheers mooncoon
 
mooncoon said:
I found myself wondering if the brazing was added electrically because using a torch, I would expect discoloured metal for some distance back.
Click to expand...

That would be true of welding. This appears to be a straight brazing. Brazing doesn't get up to that temperature.
 
Brazing requires red heat. Pretty hard to bring that area to red heat and keep the locking lug from getting too hot. Fortunately, there are two active locking lugs. Most Mauser receivers and bolts are surface hardened. A professional repair could have involved TIG welding and re-heat treatment.
 
It's amazing how good "heat sink putty" works. I have seen it used on some pretty critical areas on shaft splines and gears as well as a high pressure impellor pump vane and it kept the heat away from very effectively from everything it was attached to.

I have seen it packed into bolts when welding and brazing on bolt handles and other than a very little bit of discoloration nothing worrisome IMHO.

I am willing to bet that if the proper insulation techniques were used when that braze was done all will be well. The big thing is though that unless you were there or knew the person that did the job you just don't know. If it were mine, I would get the hardness checked with a Brinnell hardness tester against the hardness of the other side. If they are the same go ahead and use the bolt.
 
mooncoon said:
I found myself wondering if the brazing was added electrically because using a torch, I would expect discoloured metal for some distance back. The extent of the heating could be controlled with wet rags or some form of heat sink but it would still extend some distance back from the area with the actual material added

cheers mooncoon
Click to expand...

I've found if it was done with a wire feed , the part ends up with substantially more heat in it than normal torch brazing .

the only thing that might have less heat is using a tig ...... and if your going to go that route might as well fusion weld it .

the bolt looks like it was polished after the fact .
 
I see mention of the lowest brazing temperatures starting around 800C (bright cherry red).

I see the mention of the highest tempering temperatures of the 41x series listed as being around 700C (dark cherry).

Since the lowest brazing temperature is higher than the highest tempering temperature, there's pretty much no way the brazing didn't wreck the heat treatment over at least some portion of the part unless the brazing was done with some exotic low-temp-but-strong alloy, or the bolt was made of something with a significantly higher heat resistance than the 41x series.

Your call, but considering the impact of a failure (on your face) I'd either return it or destroy it to take it out of circulation.

Ulrich
 
Wow just wow , why do people with no clue do #### like this is beyond me but I think it must have to do with no clue.

Cut it up so it doesn't end up in someones gun by accident temperatures hot enough to braze are way higher than the original heat temper that it would have been drawn at for the right hardness and no doubt has been softened up considerably to a dangerous condition.
 
Yeah, don't worry guys. I want to take care of my face (and my sons' face too) too much to risk something like that. I'm hoping the seller will take it back (not really likely...), or will try to source a bolt that's work. Wish me luck. If all fails, I'll have to part this one out, at a loss.

Lou
 
Wish you lived closer, would love to have you bring her out to the farm and run a battery of test rounds thru it (fired from a tire with a long remote string of course) and just see how the lugs do react
 
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