Determining Group Sizes...?

Discussion in 'The Basics, Starting Out' started by MAELTY, Apr 15, 2003.


    MAELTY Active Member

    Mar 14, 2003
    Love this site!

    When I read here that someone has shot a 1/2" group, how is that measurement taken?

    Is it from outside to outside of fartherest holes or from the center point of these holes?

    For my own group comparisons I use the outside.

    Also, what do you feel is a repectable group size at 1000 yards? I will be shooting this distance for the first time this weekend. I'm shooting a 7MM WSM in the Model 70 Coyote. With 62.5 grains of IMR 4350 and the 162 AMAX I've been printing on average about 1 1/2" to 1 3/4" groups @ 300 Meters.

    I would really love to knock a deer dead at this distance. Your advice so far has helped me to beleive that I can. I never had a gun that gave me this chance and from what I've learned and used on here
    has me shooting and thinking that this is do-able!


  2. Tim Behle

    Tim Behle Well-Known Member

    Mar 16, 2002

    Generally Groups are measured outside to outside, then one caliber is subtracted to give a center to center distance.

    I never really noticed much effect from the wind until I started shooting past 600 yards. Then once I got past the 800 yard mark, the wind, no matter how little, meant the world.

    If you break 10" your first time out to 1,000. Stop shooting and go buy lottery tickets.

  3. Darryl Cassel

    Darryl Cassel Well-Known Member

    May 7, 2001
    Hello Tom and Tim

    Tom, as Tim mentioned, measure from outside to outside and then subtract the bullet diameter or if you have a measuring device that has the ability to measure from "center to center" is the way we do it at the Williamsport 1000 yd matches.

    The comment that Tim made as per buying the Lottery ticket is a very good one however, your first time out with a factory comfiguration I would say if you break 15" (10 Shot group) at 1000 yards during a sanctioned match your doing better then average. I'm judgeing this on the results from Williamsport over the past 16 years.

    We have had the Army team, the Marine team and a couple Navy Seals come to Williamsport from time to time over the years and the statement they make is---WE will not be back as we can't figure the wind out here. They didn't do very well at all and were soundly beaten by the regulars who have not figured the wind out there either. They have just figured a way to put 10 shots downrange as fast as 30 seconds or less before the conditions change.
    In defense of the Military shooters, most of them shot from a prone position and that in itself put those shooters at a dis-advantage against some very good benchrest LR shooters.
    I think the best group I saw from the Military shooters was 17" for a 10 shot group string.

    When a new guy comes to Williamsport, he is afraid he won't keep all 10 shots on paper. I try to put them at ease by saying, you'll do fine and I'm sure you will keep them all on the target and we will make sure we get you on paper during the sighter round. The rest is up to you.

    Good luck to you and let us know how well you did at 1000 yards.

    One more thing.
    If you shoot early in the morning or late in the evening is the best time to try for groups. The wind normally dies down during that time.
    Most sanctioned matches are set up to start at 9:00AM and if your lucky enough to get an early relay, you will, 9 out of 10 times, find that those relays have the best results of the day.


    [ 04-16-2003: Message edited by: Darryl Cassel ]
  4. Brent

    Brent Well-Known Member

    Jun 12, 2001
    As Tim said, the centers of the two farthest holes is what you're after, I get this buy measuring from the outside of one to the inside of the other... saves you from having to subtract the bullet diameter is all, which sometimes is not exactly the diameter hole that's left in the paper.

    I've shot some smokin groups at 1000 yards, most wouldn't even believe 'em, but none of them were 10 shot groups, just 3 or 5's. Ten shot groups at 1000 yards, I believe, more accurately evaluate the shooters ability to read conditions and changes or lack there of, as just too many variables are at work for most load proving and shooting technique assessments. I like aggs of 10 shot groups at 500-700 yards in calm conditions for final checks on these things for the reasons Tim stated above.

    3-5" groups have always made me pretty happy at these ranges with my equipment. I think consistant MOA or better is quite an accomplishment if you're shooting ten rounds at 1000 yards. Often 1.5 MOA at 1000 yards is quite a feat to accomplish if conditions aren't ---- near perfect, and really, how often are they.

    I'm with DC and like the early morning and late evening for 1000 yard or any range testing. Mirage and wind are usually alot less then, but the bugs in your face are at their worst. [​IMG] A comprimise in everything. [​IMG]