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Thread: A String of Failure to Fires in My ‘73

  1. #1

    A String of Failure to Fires in My ‘73

    Last weekend my Cimmaron ‘73 had a string of about 5 failure to fires. It was the last stage of the day on day 1 of a 2 day match. I bought this carbine new in 2003 and never had a problem with it. I did take the firing pin out last winter and clean the firing pin track. After the string of malfunctions I took it home and took it apart. Nothing apparent was observed. The firing pin, firing pin spring, and firing pin track did not show any sign of excessive fouling.

    I’ve run this carbine all summer without cleaning the firing track with no problems before. This match was the 2nd 2 day match in 2 weekends. The carbine had approximately 100 rounds through it the previous weekend with no problem. On the day it failed to fire it had been running fine for 5 stages of 10 rounds each.

    The failure to fires occurred after about 4 shots, then the 5 failure to fires, then the carbine fired the 10th round.

    There is no sign of a light primer strike on the ejected cartridges.

    The rifle is calibrated to .44 Special, I was using Starline brass, CCI primers, Trail Boss and my cast RCBS 44-200-CM boolit cast with scrap lead lubed with Alox. This combination has proved successful for me for years.

    I’ve ordered a new firing pin spring. Brownells did not have a new firing pin in stock. I’ll keep you posted how the test firing goes when the new firing pin spring arrives. But you know how these things go, what works at a leisurely practice session is not guaranteed to work at a match.

    Just to be sure I went out and bought a brand new Winchester (Miroku) ‘73 with a 24 inch octagon barrel in .44-40 for the 2nd day of the match. I’m really happy with the Winchester/Miroku.

  2. #2
    Have you checked your main(hammer) spring tension? It is adjustable and they loosen over time and will give intermittent "light strikes".

  3. #3
    Moderator



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    And also check the tip of the firing pin. They do break once in awhile. For parts, you can check with Will Shootem, at Pioneer Gunworks, in Springfield, OR.

    Hope this helps.

    Fred
    After a shooting spree, they always want to take the guns away from the people who didn't do it. - William S. Burroughs.

  4. #4
    Boolit Master
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    “There is no sign of a light primer strike on the ejected cartridges.”

    Does this mean that you observed a normal indentation on the primers? If so I’d think ammo rather than gun. Have you pulled down those rounds and taken a good look at the primers?

  5. #5
    The carbine has a factory mainspring with the tension screw screwed in all the way to maximum. The hammer feels and sounds like it hits with the same authority as it always has.

    I examined the firing pin, it appears to have the proper rounded point however I don’t have the Uberti tech manual to confirm the specs. I’ll probably buy another one when Brownells gets them in stock.

    The primers of the ejected cartridges showed zero dimples.

  6. #6
    Boolit Master
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    “The primers of the ejected cartridges showed zero dimples.”

    With that forget what I said, seems that you are on the right path with the firing pin.

  7. #7
    Boolit Mold ANick57's Avatar
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    Odd that it's intermittent like that. Unless you got something that lodged in the track that blocked the firing pin.. and then cleared?

    Can you recreate the failure or has it been functioning as intended since?

    The firing pin worked on your initial report after not striking five previous. Either the pin isn't being struck by the hammer, was blocked from moving to strike the primer, or the bolt face was too far from the primer for the firing pin to reach.

    So.. let's see.

    Hammer. Could it have been caught at the half-cock? Possibly *something* momentarily obstructing the fall to strike the hammer?
    Firing pin. *Something* temporarily blocking the firing pin movement?
    Bolt not fully in battery. If the lever closed, I'd think that would mean something mechanically awry with toggles, pivot points or trunions. I'd expect that to give you a feel of 'something different' as well be more consistent. But, I suppose it's worth asking?

    Definitely not an expert on '73s, just thinking out loud.

    Curious to see what you do find though!

    Nick

  8. #8
    I’m thinking the firing pin wasn’t begin pushed back by the spring in the position ready to be hit by the falling hammer, but this is just a guess and won’t know for sure until I can say it’s fixed. Right now I’m waiting for the new firing pin spring, then I’ll do some test firing.

  9. #9
    New spring came today and installed it. Can’t say I had an Ah Ha moment. On the day it failed I manually lifted the hammer with my thumb off the bolt several times and observed that the bolt did not retract under spring tension. Maybe it was fouling in the firing pin track, maybe it was a spring that needed to be replaced. Maybe I’ll never know. I’ll test it Friday at the range but guns always work when they are being tested and only fail during a match. One thing is for certain, I’ll be cleaning the firing pin track before 2 weekends of back to back high round count matches from now on.

  10. #10
    Boolit Master
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    I would tear down the action and look for a loose primer wandering around inside.

  11. #11
    This was done the afternoon of the failure before I ran out to the LGS and bought that new Winchester.

    Quote Originally Posted by jimb16 View Post
    I would tear down the action and look for a loose primer wandering around inside.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check