Browning A-bolt and Pressure

Discussion in 'Reloading' started by bamadawg2009, Apr 16, 2013.

  1. bamadawg2009

    bamadawg2009 Well-Known Member

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    Well after many weeks of waiting I finally got some berger 168gr hunting VLDs for my dads 7mm magnum. I loaded up 3 of each charged cartridges ranging from 69-72 grains of H-1000 with Fed 215 magnum primers with overall length just long enough to fit the Mag. box. I went out today and cleaned the rifle from top to bottom. Then I fired the first group with 69 grains all was fine and dandy great group for the rifle .80s, then I shot the 69.5 and rite off the bat I new I had pressure, I ejected the first shell and primer was flat as a pancake and starting to run over the primer pocket, this went for the next 2 shots as well. The group opened up to well over 1.5". I have never had such a pressure jump between the first and second load grouping and usually run full charge and never show pressure signs. My question is why such a jump in pressure with low charges. I Know everybody says magnum primers count as 1gr of powder themselves, if this is true that might make sense then Id only be 2grains under max. Anybody got a clue?

    All the powder was out of a brand new 8lb jug I just got from Powder valley 2 weeks ago so no different lot numbers and all the primers came out of the same tray.
     
  2. MudRunner2005

    MudRunner2005 Well-Known Member

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    Do they have any 8lb'ers of Varget?
     
  3. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Did you check your jump to the rifling?? My browning 300win fits the mag and only has 20 thou. jump to the rifling with its hunting load and it has got well over 1,000 round through it. Brownings usually don't have a grand canyon before the lands like remmy's do.
    You started rather warm on the charges too, after looking on hodgdon online. They only top at 70 grains on the hdy 162 and top at 64.5 on the 175 partition. I'd bet you landed at the top safe charge right away.
     
  4. bamadawg2009

    bamadawg2009 Well-Known Member

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    I just got lucky, I was checking their site every day for almost 2 months straight and they had a shipment come in I guess because they had h1000 for about a day and a half. I never did check for Varget Ive still got 5lbs in the closet.
     
  5. bamadawg2009

    bamadawg2009 Well-Known Member

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    I never did check jump I seated them the same depth as the Sierras I loaded for it. I went by hodgdons website and they had loads for 162s and 170s so I just went 1 grain over the max load for the 170s figuring for the 168. I also checked LRH and general consensus is most people were getting 72 grains for the 168 bergers.
    I will admit I probably did start a little hot considering the Magnum primer if that is true, but I usually start 1.5 grains over min load in most of my guns without ever having such a problem, unless Im loading for an automatic then I start at minimum.
    I might just have to go back to the drawing board and start over.

    Anybody else have any load data for the 7mag and 168 bergers?
     
  6. PowellSixO

    PowellSixO Well-Known Member

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    On load data they show a max load of 69.5 grains of H1000 at 2987fps with the 168 Berger Vld's. The start load they have shown is 62.5 grains as 2669fps. What kind of speeds are you getting with the 69gr loads?
     
  7. bamadawg2009

    bamadawg2009 Well-Known Member

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    I was going off hodgdons website. I went by the 170 grain data and started at 69 grains then went 1 grain over max but never made it close to max. They have no data for the 168s, dont know about velocity I was just getting a start point for accuracy then will go for speed when I find a charge it likes.
     
  8. PowellSixO

    PowellSixO Well-Known Member

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    PM me your email addy and I'll send you a picture of the 168 vld info I have.