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Discussion Starter · #1 · (Edited)
First let me say that I am not an expert material tester and have no certification in this field and am doing this strickly as a favor and for my own enlightnment as well as yours.
TRW back face 57.9 HRC
FA back face 40.5 HRC
TRW top near front 56.4 HRC
FA top near front 37.9 HRC

I have some others but I have decided that these are the most reliable. Most of the others of the FA bolt that seem fairly reliable are just under 40 HRC. My conclusion is that Thunders bolt is no where near as hard as a TRW. I am not sure what spec is for this if anyone knows for sure (no B.S., WAG-wild ass guess thank you very much) please lets us know.
Now I want to cut it up and make cross section specimens, but this will take time and is Thunders call not mine.
Oh, and yes I had to hold it steady for some of the test with my hand (probably not admissable in court) and that is not my hand in the pic but the hand of my furry co worker.

Edit: Anything below 40HRC is considered machinable with high speed cutters although it would be hard to do.
 

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Have not followed the site due to illness for the last few months; so I missed out on some things. Who makes the Thunder bolt?. I remeber Armscore use to make the Fulton Armory receiver to "Fultons" specs. Couldn't agree more about TRW bolts, a TRW bolt almost fit my Polytech with little modification.
 

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Discussion Starter · #4 ·
It's not a thunder bolt it is Thunder's bolt. He is the one that bought it from Fulton.

Have not followed the site due to illness for the last few months; so I missed out on some things. Who makes the Thunder bolt?. I remeber Armscore use to make the Fulton Armory receiver to "Fultons" specs. Couldn't agree more about TRW bolts, a TRW bolt almost fit my Polytech with little modification.
 

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Doesn't Fulton supply M14 variants to the Army?
 

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Discussion Starter · #9 ·
I think you are correct. I spoke to someone I know with a lot of experience in this field and he said I need to build a special fixture to hold it and a "micro something" tester. We have a nano indenter, but I wouldn't use it for this. It is very expensive and complicated to use. Let me state again that I am not an expert in this field. If I slice it up and machine/polish the surfaces parrellel to one another then this type of test would be more conclusive. Even if I do all that it really won't matter because I am not certified to do it, but I have prepared plenty of samples for research work and the test results have been published.


I'm no expert but I think you have to use special means to check surface hardness of case hardened parts. The standard Rockwell test doesn't work.
 

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Wow, the my Fulton bolt is over 35% softer than the TRW bolt. I think we have pretty solid evidence that the Fulton bolt is faulty. Even though Memphis didn't use a test fixture I think the test to the back of the bolt says it all due to the stability of the bolt against the test bed. Even if we don't have a "Micro" Do-hicky tester, I think the departure from TRW's spec is so far from each other that it's proof enough. I'm going to give Fulton a call about this.

Memphis, you sir and everyone here is awesome!
Maybe I should start my own company the produces quality M1A bolts and call it the "Thunder bolt" It has a really nice ring to it! GI2 I would definitely back my product up!
 

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Hardness Scales

M14 bolt drawings specify a case hardness of D66-71 as noted. This may be somewhat confusing to many since most hardness tests are done in Rockwell C measurements. I don't know what the conversion factor is, but the bolt for the M1 Garand rifle is listed as having a case hardness of C55-59. It's fairly safe to assume the M14 bolt should be the same as the M1. Therefor, the difference between the TRW and FA bolt are not quite as wide spred as thought here. Still, C40 is well below C55. The core hardness for M14 bolts is supposed to be C33-42. This makes me wonder where that leaves the FA bolt.
 

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Discussion Starter · #13 ·
http://www.carbidedepot.com/formulas-hardness.htm
This chart shows 56c = 67.7 40c=55.4d The TRW bolt fell right in the midrange not bad for a part that is likely 50 yrs old. It seems this test is not that far off. The tester is digital and you can select the scale electronically. I may look at it and see if I can do it in d, but I will have to figure out some other parameters as well.

M14 bolt drawings specify a case hardness of D66-71 as noted. This may be somewhat confusing to many since most hardness tests are done in Rockwell C measurements. I don't know what the conversion factor is, but the bolt for the M1 Garand rifle is listed as having a case hardness of C55-59. It's fairly safe to assume the M14 bolt should be the same as the M1. Therefor, the difference between the TRW and FA bolt are not quite as wide spred as thought here. Still, C40 is well below C55. The core hardness for M14 bolts is supposed to be C33-42. This makes me wonder where that leaves the FA bolt.
 

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Yes, I couldn't help but notice that the surface hardness numbers obtained, while maybe not perfect, fell in the accepted range for the CORE of the M14 bolt. In other words, if you pulled a bolt before it was case hardened at all and tested it you would get the same numbers MM got... Coincidence? GI8

I for one would love to see this bolt sectioned thru the lugs as specified on the drawing, and the core compared to the case layer. I'll bet there's no case layer at all. (See the results with the file) In fact I'll put my money where my mouth is and bet $10.00 towards a new bolt, just to see this one sectioned.
 

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I had a long talk with Fulton and was told by them that nothing can be determined without a full Technical Inspection. I explained that a hardness test was completed with comparison to a TRW bolt and I gave them the results, but they were firm that a Tech Inspection was absolutely required. They also BASICALLY said from what I understand is that the harness test is hardly conclusive and there's a lot of factors that go into testing and the harness testing scales, which makes any testing data inconclusive.

They weren’t even aware of the pictures or email correspondence I sent to them (Same ones posted here on the forum) a couple weeks ago. So they reviewed them with me explaining the receiver could be faulty such as the rear seat causing the damage to the rear of the bolt and the right lug rail of the receiver being too high causing the left lug to disengage early and right lug to strike the rail causing the impact damage.

At the end of the conversation Fulton said the bolt should be softer than the receiver and parts need to work themselves out especially after the first 50 rounds of firing. Fulton did say that they've never seen damage like this before. I proposed that if I send the rifle in for a full TI and if the bolt was faulty that they should absorb the service cost, but that didn't go far.

To me some of the information Fulton gave me makes some sence, but to say that the harness test is inconclusive and that the receiver is out of spec (wouldn't we have heard about this by now?) is coming from left field.
 

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I don't know what you can do, I'd get a USGI bolt and possibly send your old one back to Fulton. I defiantly would no longer do business with them. I would also document everything and try my best to get to Fulton's CEO, HMFIC, what ever you want to call him and explain the situation.

Before I got my James River I looked real hard at Fulton, and might have bought one. After this thread, people can hammer on Springfield all they want, but customer service counts for a lot with me and I've never heard anything bad about there service.

I can tell you Fulton will not be getting any of my money, I work too hard to give it to jerks. I do understand that they would have a need to inspect the bolt themselves, but why charge you for the privilege of sending there screw up back and fixing it?
 

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I just seems to me that, given the efforts you have gone through, and this is assuming you have been courteous yourself, they should just swap your bolt even up with the understanding that they wouldn't do it again given the same set of circumstances.

If I was Fulton, I would WANT that bolt back to see what is going on with it. If they are selling bolts that are not to spec, that is a huge box of monkeys. A bolt fails, people get hurt, hurt people (or their survivors...) sue.
 

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I was very courteous and professional about the call. I wanted to pick their brain and see what they had to say and what they would do about the current situation. They did seem a bit agitated over the phone as soon as I started to talk about their bolt.

Charlie, I agree. If I was in their shoes, I would have paid to have it sent back to me to give it a full battery of test to see what's going on. Some of us handle these situations differently I guess.
 
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