VihtaVuori published load data, pierced CCI 450, bullet weights, etc.

Discussion in 'Reloading' started by An Idahoan, Sep 20, 2018.

  1. An Idahoan

    An Idahoan Well-Known Member

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    Looking for some help...

    VihtaVuori's published data for 6.5 Creedmoor assumes Lapua brass and for primers assumes "small rifle".

    This is what I was working with:
    6.5 Creedmoor
    Lapua brass
    VihtaVuori N160 powder
    CCI 450 Small Rifle Magnum primers
    Berger 135 grain Classic Hunter bullets

    I figured that using the recipe for the 136 grain Lapua Scenar-L would be "close enough" and started working up. Working up to the published max of 46.0 grains of N160, I experienced only slight flattening/cratering of primers (nothing that different from Hornady 143 grain ELD-X factory loads). There were zero bolt face markings on the brass at any point. After shooting groups in 0.2 grain increments from 45.0 to 46.0 grains, I decided 45.8 looked promising and loaded up a few dozen for my next day on the range. That day came and I pierced a primer on the sixth round.

    My questions for the folks here are:
    1. Is there something about the CCI 450 primers (being "magnum" that is different enough from a "non-magnum" primer as to generate too much pressure?
    2. Do you think the differences between the listed Lapua Scenar-L @ 136 grains and the Berger Classic Hunter @ 135 grains could account for or contribute to too much pressure?
    3. Do you think that the issue wasn't too much pressure but rather a firing pin that is too large as Greg @ Gre-Tan Rifles suggests can sometimes be the issue?

    Thanks for the help!

    Paul
     
  2. MagnumManiac

    MagnumManiac Well-Known Member

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    Yes, I have a pressure trace and switching between a standard primer and magnum primer, even in a case as small as a 222 Rem, or as large as a 22-250, is enough to raise pressure by 8-10,000psi.

    So, you may be running right at max with your 45.8gr load, or well above it.

    Pierced primers are NOT always caused by excessive pressure, BUT in your case, I think a reduction in charge weight is in order.

    Just FYI, a small rifle primer handles far more pressure than a large rifle primer. Both the cup and pocket have far less area, meaning it takes more pressure to obturate them past their elastic limit.

    Cheers.
    :)
     
  3. bigedp51

    bigedp51 Well-Known Member

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  4. bigedp51

    bigedp51 Well-Known Member

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    The small rifle primers are thinner and will "not" take as much pressure as a large rifle primer. And a reason why primers with a cup thickness of .025 are recommended to keep from piercing primers in the AR15. And why CCI 400 and Remington 6 1/2 primers are recommended for lower pressure cartridges like the .22 Hornet.

    [​IMG]

    Below a CCI-400 primer with a .020 cup thickness fired in a AR15 rifle. So the thinner cup on small rifle primers do not make them stronger than large rifle primers with a .027 cup thickness.

    [​IMG]
     
  5. barefooter56

    barefooter56 Well-Known Member

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    Paul,
    I had the same issue with CC450 primers with a Remington .308 action. You need to contact GRE-TAN and get the firing pin turned down and bolt face bushed. Once I did that. The issue went away and I was able to work the load up further. With our CLASSIC HUNTER bullets. In most cases your load development will consist of seating the bullet to the published magazine length (2.800 COAL) of the round you are testing. Then work the powder charge back up slowly checking for pressure signs and accuracy. If you need any BERGER load data for N-160 and the 6.5 135gr CLASSIC HUNTER bullet. Please send us an email at [email protected] . Please include: your name. daytime contact phone number, cartridge, powder and bullet. This usually takes about 5 working days. If you have any other questions please feel free to contact us at any time! Thanks for using our bullets and powder Paul!
     
  6. An Idahoan

    An Idahoan Well-Known Member

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    Phil,

    I really, really appreciate the help and the advice. I have been considering the Gre-Tan work for a little while now, but I asked about CCI 450s and pressure because I don't want to chase the wrong solution (Greg himself says that sometimes the problem isn't geometry, but too much pressure). Either way, I know it won't hurt anything by having Gre-Tan turn the pin and bush the bolt face.

    I just emailed your team at the address you provided. Thank you for that advice!

    I am curious about your recommendations for seating depth and the Classic Hunters. I know they are not as sensitive to seating depth as the VLDs, but after reading Getting the Best Precision and Accuracy from VLD bullets in Your Rifle by Ed Stecker, I am inclined to try out his recommendation with the Classic Hunters. Is there another recommendation or adaptation of his prescription that I should apply to the Classic Hunters?

    Thanks again for the help!

    Paul
     
  7. barefooter56

    barefooter56 Well-Known Member

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    Paul,
    You are very welcome! Bob has your email and you will be hearing from him next week. In regards to the CLASSIC HUNTER bullets. These are a HYBRID design bullet that has a SAMMI length nose dimension for a bullet made to be used at magazine length. Unlike our ELITE HUNTER HYBRID or VLD hunting bullets that have a long "over length" nose dimension. Hybrid bullets are not as finicky as the VLD bullets in regards to bullet seating depth because of their tolerance of "jump" to the lands. With my .308 Winchester M-70 that has a throat so long that the 185gr CLASSIC HUNTER bullets base was above the cartridge case mouth if seated to touch the lands. I seated the bullet to 2.805 COAL to give me some room for bullet nose variance ( Usual COAL of the .308 WIN is listed at 2.810in) . Then worked the load up slowly checking for pressure signs and accuracy and got .4 groups at 100 yards.
    Try this before doing any bullet seating depth testing.
     
  8. An Idahoan

    An Idahoan Well-Known Member

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    Thanks again. Bob actually got back to me today. His answer was helpful, but leaves me with more questions for later ;)

    That is one long throat. 0.4 @ 100 is outstanding in my book!
     
  9. An Idahoan

    An Idahoan Well-Known Member

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    Thanks for this. Do you think that the larger the case capacity, the smaller the difference in pressure between a "standard" and "magnum"? I think you're right that I could very likely be over pressure.

    I am with you on small vs. large. This would be true even if the thickness of the cup was identical for the reasons you state. But the thickness cannot be ignored as bigedp51 points out. Both are factors.
     
  10. MagnumManiac

    MagnumManiac Well-Known Member

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    :)Yes, pressure differences get less as capacity increases, and in my 505 Gibbs, as an example, a 5gr increase in powder from 144gr to 149gr gave an increase in pressure of around 8,000psi and velocity increased only 60fps. Recoil at 149gr, 600gr RN @ 2350fps was too much for me, I went back to the 2150fps load.
    So, in the case of pressure differences from primer type, then it would get less as capacity increased. My 25-06 shows an increase of 8,902psi with the SAME load by just switching to a magnum primer, it’s still under max, but is not kind on Rem brass, Win brass handles the increase though.

    Cheers.
    :)