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Hra .u. Bolt failure

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    Hra .u. Bolt failure

    CT KID over on cmp and m14 forums had a left lug sheared off on his .308 M1 .He sent it to me and I did a detailed inspection of the bolt and found all mechanical specs well within blueprint tolerances .
    The surface hardness was right at max spec of 61 HRC but the core was near dead soft at 15 HRC. The issue and cause I found was the case depth exeded the max thickness by over three times blueprint specs and was at .060'' in places.

    Left lug contact as also more previlient than the right lug so coupled with max hardness,case too thick,core to soft, improper lug contact resulted in failure to this bolt .Luckily there were no injuries and no apparant damage ti rifle.

    If you have one of these bolts in a frequent shooter I strongly advise detail clean and inspect lug contact , check for damage or cracks around locking lugs just to be safe .

    Bolt were made and heat treated in lots so its a good bet more of these are out there ,I know of no other failures or documentation any were discovered by inspectors . UNDERWOOD did have M1 Carbine bolt failures .








    #2
    few more







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      #3
      I did make a cool cutaway of the firing pin hole .



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        #4
        Very interesting. Thank you for posting. Too bad Underwood did not stamp heat lot numbers on the bolts like SA did.

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          #5
          Thanks for the info. I checked mine. I have U and .U. but no .U..

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            #6
            The third dot on right is HPT Proof dimple they are randomly applied to different areas on top of bolt.

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              #7
              Thank you for posting this, I have a recent SG in 3006 with bolt stamp- 6528287HRA
              U.W. 058
              Different lot I hope.

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                #8
                The failed bolt was made by UNDERWOOD .U. was their code , your bolt was made by UNIVERSAL WINDINGS .U.W. was their code

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                  #9
                  Originally posted by BehindEnemyLines View Post
                  Thank you for posting this, I have a recent SG in 3006 with bolt stamp- 6528287HRA
                  U.W. 058
                  Different lot I hope.
                  As stated different bolt completely, even if it weren't I still wouldnt worry. In over twenty years this is the first Garand bolt lug I have ever seen or hear of failing. Its not common

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                    #10
                    No need to worry but by all means if you do a lot of shooting with one ,takes just a few minutes to get a visual inspection.
                    This bolt had brass embedded in the second crack so it fired who knows how many rounds before fracturing.

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                      #11
                      Thank You for sharing the knowledge!

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                        #12
                        Originally posted by IRON WORKER View Post
                        The failed bolt was made by UNDERWOOD .U. was their code , your bolt was made by UNIVERSAL WINDINGS .U.W. was their code
                        Per the book "The M1 Garand: Post WWII by Scott Duff page 95 HRA U.W. was the last issued bolt used by HRA. Makes you wonder why they switched vendors.

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                          #13
                          The American Rifleman magazine October 1983 issue page 43 shows a HRA U. bolt with a sheared right lug. Title of article is "The Mysterious Slam-Fire" by Wayne Faatz. pages 42, 43, 73, 74, 76, 77,78,79. and 80. The bolt sheared in a M1 Garand match rifle chambered in .308. The incident occurred during a rapid-fire string during a match. Faatz concurred the bolt sheared do to an out of battery slam fire. Personally I concur with Iron Workers' conclusion the bolt in the other incident was defective.
                          Springfield Armory Inc, (SAI) at one time included copies of above article with all semi auto rifles they sold along with a warning not to use handloads.
                          Last edited by RDS; 10-22-2018, 01:04 PM. Reason: Information added

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                            #14
                            Excellent RDS , Thanks for the additional info.I might send this bolt off for spectrum analysis .The metal may not even be correct.I've never seen the core in 8620 remain near dead soft ,it's usually in the upper 30's to low 40 .

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                              #15
                              I cut in half a second HRA .U. bolt , this one checked ok 60 HRC on the surface and the core hardness around 40 HRC and a nice even max spec case thickness . I have five more .U. bolts I'm going to cut in half just for curiousity . Thanks to some info provided to me I found out that Lesonna corp which was formerly UNIVERSAL WINDINGS who made the failed HRL M14 bolts 6,960 bolts were scraped.
                              over 30,000 bolts had to be inspected resulting in over 1200 man hours of inspection .H&R sued Lessona Corp.



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