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Bolt and Op Rod Repairs


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#1 StrangeRanger

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Posted 29 May 2019 - 01:14 PM

It's no secret that fresh bolts and op rods are getting very rare and expensive but that worn parts are plentiful.  Is there any gunsmith out there who is welding up the worn areas, re-heat treating the repaired areas and grinding the parts back to the original configuration?  I know this would be an expensive process but the price and availability of serviceable parts could make it viable if not now then in the very near future.


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#2 mattnh

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Posted 29 May 2019 - 02:18 PM

My 2 cents as an amateur blacksmith...

 

Any added weld material is going to be metallurgically different than the existing material (possibly very different).

This means that its potential annealing/machining/re-hardening will be different at different spots.

 

There will always be greater potential for failure at a weld joint; the hardening process

will greatly aggravate the stress point.

 

Different alloys can require totally different quench processing and tempering process.

Two bolts that look the same could be made of different materials and processed very differently.

For example, some metals require oil quench and other require air quench to properly harden.

 

Repairing op-rods with weld prob. wouldn't be that big of a deal; however, I would NOT

do that to a bolt (or barrel) where a failure could be catastrophic.

 

No way would I ever use a bolt that somebody heat-treated in their garage

much less welded-on, annealed, machined, normalized, and then and heat-treated in their garage...


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#3 StrangeRanger

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Posted 29 May 2019 - 04:25 PM

I'm not interested in amateur "garage" repairs either.  I'm hoping that there is a competent professional doing these repairs


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#4 BillyDixon

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Posted 29 May 2019 - 04:53 PM

i have delt with a few verry compent welders out here in silicon valley,some have there own shops, and do special certifyed work for the likes of lawrence livermore labs,aec. so what are you looking to pay to have an op rod welded?these guys charge way in excess of 100.00 per hour, they have a lot of overhead with osha etc most cant be bothered with such a small job with set up time etc, now if you had say 100 op rods to weld we will talk business, just sayn


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#5 StrangeRanger

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Posted 29 May 2019 - 08:12 PM

I'm not looking for a shop that has the capability, there's no real shortage of those.  I'm just asking if there's someone in the Class 3 community who is already doing the work.  It just seems that there's an admittedly niche market that is going unserviced.  There's no shortage of inexpensive bolts with chipped left lugs and/or worn right lug radii but right now they're more useful as paperweights than as firearm parts


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#6 Normal1959

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Posted 30 May 2019 - 03:00 PM

I bought new (later date) bolts until i reached 10 and stopped buying. The later date bolt are much better metal. Same as cash with ebay, spare parts and maybe a good investment. Plus it solves the OP's problem.

Eric

 

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#7 BPinFL

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Posted 31 May 2019 - 08:07 PM

Sorry Chief, it just cant be done! Read what Matt said.

The chipped bolts are from poor maintenance and improper operation of the weapon.

There are some things you cant fix with welding, super glue or bandaids.

BP


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#8 mattnh

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Posted 31 May 2019 - 08:41 PM

IMHO, OP rods would be no big deal to repair with some Tig-weld followed-up by re-machine

(the end result wouldn't be as good as a new op rod)

 

Technically, a bolt probably could also be repaired, but would require likely eddy current testing after welding/machining/hardening,

then a live proof shot (to ensure bolt doesn't fail at required peak overpressure),

followed by re-testing if it didn;t obviously fail (dye test at a minimum).

 

But why???

Just buy brand new ones from USO, they are avail (for a price), and are better (last longer and not as failure prone).

 

Metallurgy has advanced A LOT  in the last 50yrs...


Edited by mattnh, 01 June 2019 - 12:06 AM.

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#9 johnsonlmg41

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Posted 02 June 2019 - 07:50 AM

Solutions looking for problems?   The chips in the bolts are an inherent design issue and the fix is to let it chip, stone off the rough edge per the manuals, and the problem is solved since the bolt now is worn to it's actual correct working dimension.   The op rods could be welded and re-cut if necessary, or just re-cut, but I've not seen one wear that bad yet.  You can weld on it, but then you have to decide whether you want to replace sears or fix op rods.  One of them is going to wear faster than the other depending on the hardness.  Likely the op rod was picked as the wear item during design.....or not, since government was involved in the design.

 

Or as suggested, buy new parts, no shortage just higher prices than what guys want to pay after buying surplus parts for next to nothing.  


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