My Berger 7mm hybrid BC test

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by elmerdeer, Aug 18, 2010.

  1. elmerdeer

    elmerdeer Well-Known Member

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    Hi guys I bought some berger hybrids 180gr bullets with a G7 BC of .345 and I decided to run some tests on them at semi lomg range 625 yards to see if they would get that BC. I have a Hoover metplat trimmer and poining die, so I sort 150 bullets and there is .002" variance at the ogive, pretty good so far. I start to metplat trim them about .005" and then point them. So if theory is correct I should loose about 2% BC and gain lets say up to 8% BC, so were 5% gain on BC which would bring the BC of this bullet up to G7.362 BC.
    Well I shot them out to 625 yards and was low about 1.5 MOA, so I come back look at my speeds from my chrono at 12ft and decide to put a chrono at 200 yards to see what speed I am getting out there. Then I run those numbers with my 2 average velocities and I come up with my ne BC for these 180gr hybrid Bergers and I am a little off Bergers numbers.
    The BC I got was .327, so it seems they are not as high as I thought.
    Has anyone seen the same thing with these bullets?
    But as far as acurracy they are pretty good if I do my part and the conditions are good, i get Half MOA or less at 200yards.
    And when I shot at 625yards the bullets went through a quarter inch of steel like it wasnt there. So I think it should be a good hunting bullet. I shoot a 7mm Dakota caliber, Stiller predator action, with a 24.5" Rock barrel 8.73 twist and my load is 74.5grs Retumbo seated .015" off the lands and I am getting 2979 fps avg with low es and sd numbers.
    Let me know if what I did was the right, as I am pretty new to long range shooting.
    Thanks
    Elmer
     
  2. sniperjwt

    sniperjwt Well-Known Member

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    I would say that the modifications that you did to the bullets may have had some impact. I have heard that trimming the meplat will reduce by 2% but i have not herd of any process that will up the BC by 8%. That being said normally companys up the numbers a little to make them look better thats why its always a good idea to check your drops at the ranges you will be shooting at and dont trust the ballistic calculators except to get you close.
     

  3. coyotezapper

    coyotezapper Well-Known Member

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    Is this the HPBT 180 or something new???
     
  4. elmerdeer

    elmerdeer Well-Known Member

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    No it is a new bullet design it is that combines 2 types of ogives.
    Elmer
     
  5. tresmon

    tresmon Well-Known Member

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    Per pointing 180 hybrids:

    In conversation with Litz of Berger bullets told me that while pointing bullets helps smaller caliber bullet significantly more than larger cal bullets (it's a bullet diameter to point (meplat) diameter ratio thing) the 180 hybrid is an exception because the manufacturing process of this particular bullet leaves it with a larger than normal meplat for the bullet's size. He told me pointing the 180 hybrid would give it about an 8% increase in real world BC.....
     
  6. Hunter66654

    Hunter66654 Well-Known Member

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    Does that mean that you don't trim the bullets first?
     
  7. NZ Longranger

    NZ Longranger Writers Guild

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    Our results so far with the 180gn Hybrid have given us an average G7 BC to 1000 yards of over .340. This was in an extremely skinny fluted barrel we were testing that definitely seems to produce more yaw over the first 100 yards or so. Its a 26" no.3 (depending on who's contours you're quoting) measuring .600" at the muzzle, chambered in the 7mm FatMax (the new 300 Norma necked to 7mm, and fits in a modified short 700 Remmy) producing over 3300fps at 65,000 psi. We got an average of .335 G7 to 600 yards, so they certainly are settling into a pretty good BC to achieve .341 G7 average to 1000 yards. Accuracy at long range has been superb with almost no vertical at 600 and 1000 yards.:)
    More testing in other calibers shortly.
    Greg
     
  8. nddodd

    nddodd Well-Known Member

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    Hey Elmer, trying to revive this older thread. My custom 7mm Dakota will be here Monday and I plan on shooting the 180 hybrids. Just curious if you've tested any other powders with this bullet or if you stayed with the retumbo.

    Thanks
    Nathan
     
  9. elmerdeer

    elmerdeer Well-Known Member

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    Hi Nathan, I have shot H1000 with it out to 1000yards and its quite accurate but I think its more
    temperature sensitive than the retumbo I'm using, shot both powders at 75 and 15 degrees and it seems that h1000 lost about 50fps in the change while retumbo was hardly noticable.
    But I havent repeated the test if you'd I'll go into my notes and give you my findings.
    Emler
     
  10. nddodd

    nddodd Well-Known Member

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    If you don't mind pm me your loads you tried in retumbo and h1000 and also the primers you tried as well.

    I appreciate your help, it's pretty hard finding info using this case and bullet. I sent you a pm on accurate shooter asking the same thing too.


    Nathan
     
  11. elmerdeer

    elmerdeer Well-Known Member

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    Np Nathan will send them to you later on tonight.
    Elmer
     
  12. Tumbleweed

    Tumbleweed Well-Known Member

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    Elmer, one thought. Are you using a BDC reticle or dialing a turret? It also could be that your scope may not be tracking correctly if you are dialing. I have run into this recently where the MV and B/C were right but drops on target were not coming out right. I did a scope tracking test at 100 yards. I fired two shots at the 100 yard dot, dialed up 10MOA and fired two, dialed up 20MOA and fired two and then finished off by dialing up 30MOA and fired two more. I measured from the first two shots at 100 with a tape up to the center of each of the pairs and was able to determine that the scope was undertracking explaining why my poi had been low. Just remember to use one inch plus 3/64 for each MOA you measure. Not 1". This is a very revealing testlightbulb