Primer strike issue 700 Rem

Discussion in 'Gunsmithing' started by Broz, Mar 28, 2013.

  1. Broz

    Broz Well-Known Member

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    I have been fighting an issue with a new build. I am not getting a strong primer strike and having many misfires.

    .338 EDGE not built by Shawn.

    700 Rem long action, no J-lock with a PTG light weight pin assembly. Also the firing pin bore has been bushed.

    The pin extrudes .062" when in the fire position.

    The pin bore to pin has about .003" clearance

    The strikes on the primers that didn't fire look a little weak to me as far as depth, but I have no way to measure it.

    The head space between a fired case and one that didn't measures .001" to .0015" I set the shoulder bump die up to just bump the shoulder and also measure the shoulder on fired and unfired to be sure.

    I have some of the new brass from Shawn and I got a mis-fire on the very first shot from this rifle. The next 19 rounds fired fine. The 19 unfired case rounds, that fired, were tight closing the bolt, so I bumped the shoulder back just enough for a light smooth bolt close and the next 8 out of 10 didn't fire. I pulled those 8 bullets and sized the necks, re-primed, charged and seated the bullets. the first 2 fired, then some mis fires, and 2 more fired for a total of 4 out of 8.

    I did clean the bolt inside and out, de-burred the inside of the pin bore, flushed clean, blew out with air and lightly lubed with light gun oil.

    I also have cycled the pin in the bolt shroud to make sure of no interference. It is smooth with no hang ups.

    Not sure what to do next. It has me scratching my head pretty good.

    Any help would be appreciated.

    Thanks
    Jeff
     
  2. J E Custom

    J E Custom Well-Known Member

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    I have seen this before with the light firing pin set up.

    I would try a standard firing pin to see if the added weight (inertia) would solve this problem.

    Also some rifles have a firing pin spring that is to large and snakes down the firing pin and
    rubs on the inside of the bolt Slowing the lock time. It is easy to diagnosis because when you
    remove the firing pin you can feel the drag on the inside of the bolt.

    Some benchresters wont use the light firing pin because of the inconsistency.

    Hope this helps.

    J E CUSTOM
     

  3. Wile E Coyote

    Wile E Coyote Well-Known Member

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    I can second JE Custom on the light pin theory and heres my experience.

    I've been fighting a similar problem to yours (mis fire with a light strike) with a relatively stock Rem 700, .223. A long time ago I changed the firing pin and spring to a Tubb Speedlock with their Chrome silicon spring. Up until this Winter, everything went bang when it was supposed to. The only fault I had with the setup was this pin was way too loose in the bolt face and even moderately light loads showed some primer flow.

    Then while hunting coyotes in January it started to mis-fire with a very light strike. I've had a Hollands oversize pin and spring on the shelf for this gun and this afternoon, I fitted the pin (just a bit tight but free) and assembled.

    I fired a few rounds before it got dark and each fired with no primer flow. When dry fired now it definitely feels more solid.

    The Tubb pin and spring weigh about 475 grains and had a protrusion of .052" while the hollands setup was about 750 grains and protrudes .057."

    I'm going to find the camera and take a pic of the various fired primers and post again.

    Hope this helps without confusing.

    Pete
     
  4. Broz

    Broz Well-Known Member

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    I do feel it could be an inertia problem too. I have a spare stock firing pin assembly , but it has a larger tipped pin. My light pin is .059" So I will either need to turn down the stock pin tip, or open up the bushing in the bolt.

    What is the recommended clearance for the pin to pin bore?

    Thanks for the help guys.

    Jeff
     
  5. Wile E Coyote

    Wile E Coyote Well-Known Member

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    According to the paper with the Holland oversize the clearance should be .002" between the pin and the bolt. And "The firing pin should protrude ... a minimum of .050 and a max of .060."

    The case and loose primers on the left are with the lightweight pin and those on the right are with the new pin. I must have tossed the "struck but unfired" primers and have none to show.

    Pete
     

    Attached Files:

  6. J E Custom

    J E Custom Well-Known Member

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    One other thing Broz.

    With the 338 Edge my guess is that you are using the Fed 215 If so the primer cup on the 215
    is very heavy for use in magnum cartridges and will resist flattening and with a light firing pin might
    also be to strong/ resistant to proper firing pin strikes.

    Just something else to try changing before you go back to the standard firing pin.

    J E CUSTOM
     
  7. Broz

    Broz Well-Known Member

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    Jerry and Pete, Thanks for the replies. I just turned the tip of a standard steel firing pin down to .0025" under the bolt pin bore and put that assembly together. The sound of a dry fire alone gave me a good feeling. The light weight set up always sounded weak to me. Then I took it out and chambered a round that had misfired earlier. I pointed it at the wood pile and let her fly...gun)

    It fired! I had tried re-firing these rounds earlier and they would not go on the second hit either. So I felt I gained ground. Then when I visually inspected and compared the strike form the newly installed steel assembly to the others from the LW assembly there is a definite difference. The new strike is noticeably deeper.

    So I will resume testing tomorrow and report how it goes.

    Thanks for all the help, it is appreciated.

    PS: Man! a 300 gr Berger @ 2835 fps does some serious damage to a chunk of fire wood from 15 ft.:D

    Thanks
    Jeff
     
  8. bassin93

    bassin93 Well-Known Member

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    Broz, not to change the subject but, you mentioned brass from shawn, is that the betram that was headstamped 338 edge? He had talked about it a bit at the class I was at last june but hadn't heard if he had gotten it in. Thanks.

    Hey, by the way, I am now using 103 grns of the RL33 and spittin the 300 SMKs right at 3000fps with the same pressure signs as the 92grn loads of H1000 @ 2840.
     
  9. Broz

    Broz Well-Known Member

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    Yes, this is the Betram brass Shawn had made.

    Have you done and testing RL 33 to see if it is temp stable yet? I have not used it yet but worry this could be an issue for long range from what I have seen with the other RL powders.

    Jeff
     
  10. Broz

    Broz Well-Known Member

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    Follow up on the soft primer strike issue. I replaced the light weight pin and spring assembly with a standard Remington assembly and took the rifle back out today. I had 4 rounds left that didn't fire before and took them as well. Before, a second try still would not fire them, no surprise right:rolleyes:. But with the steel pin and stronger spring they all fired as well as all the other rounds we chambered.

    Tonight I called and talked to the smith that built the rifle. He was not too surprised I had an issue with the light pin assembly. He has seen it before. This rifle was built some time ago and never put to use. He has since adopted the the plan of always installing a stronger .032" firing pin spring with all and any light pin used. He said this will cure all problems. So he is sending me the new spring to fix the original assembly. He feels it would be better to reinstall that assembly as he had "timed" it.

    I wanted to hear his opinion as he is a well known and highly respected smith. He has built championship winning rifles. So, I asked him what he felt a light weight firing pin brought to the table. He quickly said " Just what you have just experienced" " Like the thicker barrel lug, it is something many request but really has no benefit over the factory stuff if it is trued and installed correctly".

    The rifle shot pretty good today. We engaged a 3/4 moa rock at 1450 yards with a 10 mph wind. Cold bore shot grazed it and the second shot took off the edge. It is now a 1/2 moa 1450 yard target for next time.:)

    Hope to take the rifle out for some long work soon.

    Thanks to all that helped here. I will make a final report after I have installed the spring and LW pin again and let you know if it too works.

    Jeff
     
  11. DCGS

    DCGS <strong>Official LRH SPONSOR</strong>

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    Broz, I ran into this with a 300 win mag I built for a customer. When I figured it out and changed the spring everything was fine. When you take the spring out lay them side by side. When I did that the light weight asy spring was shorter than a stock one. Will be interesting to see if yours is. Just curious, how did you check the clearance in the pin. I have a set of gauge pins that I check the size of small holes with. Some times it is not all that accurate with calibers. Dan
     
  12. J E Custom

    J E Custom Well-Known Member

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    That is good news Jeff !!!

    Sometimes the small things can eat us up.

    Good to hear your smith feels the same about the problems with the light weight firing pin.

    I also like to use the heavy spring as long as it does not snake(To large diameter) and drag on the inside of the bolt.

    The light weight firing pin Is an improvement in lock time if the weapon has a slow lock time, but sometimes the advantage of the standard pin is dependability.

    A very good bench rest shooter told me that he had tried the lighter firing pins and even though he
    had no issues with them failing to fire (They normally use standard Match or bench rest primers
    with thin cups) he did notice SD numbers went up slightly.

    He thinks with less inertia in the pin, the burn rate of the primer is more inconsistent.

    In your test, If you chronograph the loads with and without the light pin It would be interesting
    data if you have it.

    If you do have /get the data it could help all of the long range shooters.

    Let us know how everything goes

    J E CUSTOM
     
  13. Broz

    Broz Well-Known Member

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    DCGS, I used a set of wire drill shanks to find one that fit, then measured it. Then measured the pin and the drill shank with a micrometer.

    I will compare springs too.


    JE, Challenge accepted. I will run some through the Oehler 35 with both. That would be a good thing to know. If I learn a path to better and more consistant ES from this it will make it a worth while venture.

    Jeff
     
  14. bigngreen

    bigngreen Well-Known Member

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    Very interesting to see the issue worked out, one to keep in the back of a guys mind for future trouble shooting!!