What's more important, ES or Group Size??

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Jumpalot, May 2, 2011.

  1. Jumpalot

    Jumpalot Well-Known Member

    Messages:
    384
    Joined:
    Oct 3, 2005
    I'm working on some loads for my 7mm Remington Mag. This rifle will be used for max 600-800 yds. hunting. I have a load that shoots 1/2" at 200 yds. but has an ES of 32 fps. I also have a load that shoots just over 1" at 200 yds. but has an ES of 14 fps. I have not had a chance to shoot farther yet. I will shoot farther to verify drop charts and to check groups as soon as the wind stops blowing. But I wanted input on which load I would be better off pursuing.
    Thanks.
     
  2. MTBULLET

    MTBULLET Well-Known Member

    Messages:
    1,056
    Joined:
    Jul 16, 2007
    group size. ES is just another "tool" to help fine tune, but shooting good groups is better than a tiny ES.
     

  3. backwoods83

    backwoods83 Well-Known Member

    Messages:
    2,206
    Joined:
    Jan 8, 2011
    I'm not bashing but I'll take a .5moa group with an ES of 2 over a .25moa group with a ES of 15 tiny grounds are not always the best, the higher the ES at the chrony just think about what that spread will be at 600yrds, a ES of 25 could be 125 at 600 and will not be consistent, this not opinion either it is fact, any 1k ibs shooter will tell you the same.
     
  4. J E Custom

    J E Custom Well-Known Member

    Messages:
    7,266
    Joined:
    Jul 29, 2004
    They are both important.

    What you want is a good group and a low ES for long range shooting.

    A good ES means that you have a good consistant Case, powder,primer and bullet weight
    combination .

    Good groups may mean that your rifle likes the bullet and velocity your using.

    At close range (100 to 300 yards) a good group is all you need.

    Try changing primers and/or powder to improve the ES while maintaining the same velocity
    and bullet.

    J E CUSTOM
     
  5. trebark

    trebark Well-Known Member

    Messages:
    3,475
    Joined:
    Jan 16, 2008
    J E Custom is right (as usual). You need a balance between group size and ES. To determine how small an ES you need, just run the numbers....

    Lets say that your 7mag shoots .5moa groups with the 168VLD at 3000fps (average), with an ES 32. Check the variance at 800 yards with a velocity of 2984fps and 3016fps. Then, depending on the variance you can determine if that variance is too much for the target at which you are shooting.

    Continuing the example, lets suppose that this velocity variance provide you with a .25moa variance at 800 yards. This doesn't seem bad until you add the average .5moa group. This would mean you have the possibility of a .75moa variance at 800 yards. that's roughly 6" and is outside the the magic 8" kill zone on a deer (remember, you are shooting at the center of the kill zone, so it's a 4" radius). In this example, an ES of 32 is too much. You would need to roughly cut that number in half to 16.

    Generally speaking, I look for .5moa accuracy (or better) with an ES of 15 (or less) in nonmagnum cartridges.
     
  6. Jumpalot

    Jumpalot Well-Known Member

    Messages:
    384
    Joined:
    Oct 3, 2005
    So how can I shrink group size of the load that has a good ES? It will print two shots together (within 1/2") and throw the third out an inch. It will consistently put the first two shots right next to each other and then throw the 3rd low and left. Is this something that can be fixed with seating depth? What about a different primer?
     
  7. noneck180

    noneck180 Well-Known Member

    Messages:
    159
    Joined:
    Sep 16, 2009
    what are your loads powder, bullet ? brass ? neck turned? neck sized?..
     
  8. edge

    edge Well-Known Member

    Messages:
    1,088
    Joined:
    Nov 4, 2005
    Go to your hunting property where you can shoot 800 yards and find the load that gives the best group. It probably has the best ES too, but at your max range the group will tell the story.

    edge.
     
  9. backwoods83

    backwoods83 Well-Known Member

    Messages:
    2,206
    Joined:
    Jan 8, 2011
    Well said, I wasn't saying that group size doesn't matter but giving up a little in group size is better than having a ES that's way to high. I think you should try a new load combo and try to get your ES under 10 if you want to do your best at 800 yards. Even if it doesn't shoot but 1.25moa at 200 that will keep you in or very close to a 6" group at 800.
     
  10. J E Custom

    J E Custom Well-Known Member

    Messages:
    7,266
    Joined:
    Jul 29, 2004
    It sounds like you may have a bedding problem or the barrel is heating up.

    What you have is a good hunting rifle but not a match rifle (One or two shots are all
    you need) .

    Check the ES on the first two and if they are way apart it is still a load problem , but
    may also be bedding and or heat.

    You can verify this also by shooting one shot and waiting 10 to 15 minutes before the next
    shot is fired.

    If conditions (Wind,Temp ETC) have not changed the groups should improve if its the bedding.

    J E CUSTOM
     
  11. trebark

    trebark Well-Known Member

    Messages:
    3,475
    Joined:
    Jan 16, 2008
    Two next to each other and throws the third out of the group...bet you're shooting VLDs.

    Adjust only one thing at a time, your two options are tune seating depth (would be my first option), then maybe tweak the powder charge up/down .2 or .3 grains
     
  12. Jumpalot

    Jumpalot Well-Known Member

    Messages:
    384
    Joined:
    Oct 3, 2005
    Shooting 168 Bergers, Norma Brass, CCI 250 Primers and H4831 powder. Had no luck with the 180 Bergers. The H1000 and Retumbo are producing a lot of smoke and carbon fouling.
     
  13. backwoods83

    backwoods83 Well-Known Member

    Messages:
    2,206
    Joined:
    Jan 8, 2011
    I'll probably get bashed for this but oh well. I do not know what your seating depth is but if I were you just for s#@ts and grins I'd jam them .005-.010" in the lands and find a good charge of IMR4350 (probably in the 60-64grn area or more with Norma brass), and set that off with a CCI BR2 or Fed210M, just because that's a good paper punching 1k load doesn't mean it won't roll a whitetail at 800 yards!
     
  14. trebark

    trebark Well-Known Member

    Messages:
    3,475
    Joined:
    Jan 16, 2008
    It seems common for the VLDs to throw one round out of the group. I have not yet discovered the voodoo that corrects the issue. I have been able to reduce the problem with seating depth tweaks though.