Learned something new today at least new to me

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by eaglesnester, Apr 12, 2010.

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  1. eaglesnester

    eaglesnester Well-Known Member

    Nov 11, 2007
    I was trying to make Burger bullets shoot, so I read the article on COAL and how to find the sweet spot. The technique for finding sweet spot works. It also taught me that your POI will vary wildly with different COAL and distance to the lands. I had my Remington 30/06 BDL straped in a gun vice on a bench at 200 yards. I fired the first 6 shots (two 3 shot ) groups with the bullet .,010 off the lands. Went down changed targets and fired the second string (two 3 shot groups) with the bullets
    COAL at .050 off the lands. I immediately noticed that the POI and grouping was completely different from the first group as was the next group and so on. My tightest grouping was with the COAL at .090 off the lands. It did no good at all to try and adjust the scope to correct for the wildly varring scattered groupings. Each string with a different distance to the lands .010, .050, and .090 and .130 the groups were radicaly different and did not even look like they were fired from the same gun. I did not touch the scope reticles.
    So I learned that COAL effects POI. I have been trying to figure out for 3 years why my rifle shoots different every time I load up a bunch of bullets and try to zero and why is my POI so much different from the last time I shot the rifle. By not paying any attention to coal I was shooting in circles and never getting anywhere. I would not have believed that COAL could effect your group and acccuracy so much. So from now on I will ensure that my personel COAL for the 30/06 is .090 off the lands.
    Now on the other hand Burger bullets shoot very accurate in my 300 Weatherby and it does not seem to matter vary much lhow close or how far the bullets are to the lands. Weatherbys jump the bullet quite a bit anyway as this was Roy's grand plan for getting the velocity so high. I am getting 3 inch groups at 400 yards all day long, a very interesting rifle indeed.
    Cheers & Tighter Groups: Eaglesnester
    Last edited: Apr 12, 2010
  2. elkaholic

    elkaholic Official LRH Sponsor

    Dec 4, 2008
    Normally the Bergers like to be closer to the lands than that, but whatever works. My rifles generally shoot higher or lower with coal changes and yes, it makes a BIG difference.....Rich
  3. Mikecr

    Mikecr Well-Known Member

    Aug 10, 2003
    This is common Eaglesnester.
    Now to 'learn' what causes this.......

    To me, it's the biggest mystery in ballistics.