G&R Tactical
Page 2 of 6 FirstFirst 1234 ... LastLast
Results 11 to 20 of 53

Thread: Let's Talk About "Accuracy"

  1. #11
    Join Date
    Jan 2011
    Location
    Nude Hampster
    Posts
    624
    Feedback Score
    0
    Jack, excellent work here. As an 0331 we used mils constantly, especially after MGLC and the Division Schools. Besides breaking off a few weak Marines, we learned those values. Mils, meters, mil radians, all that fun stuff. Later having a HOG as my spotter with a 240B in a fixed position, we could make some music.

    One of the biggest takeaways from this is those four target pictures. We actually used those same images and descriptions in training people to machine using our new 5 Axis Mills. In weapons training, I've had more success explaining it the way you have.

    *Accuracy* is a reflection of your "input" variables. In this case it could be ammo load data, performance based on anticipated trajectory, dope and wind call, etc. The shooter must know these inputs and figure them as a mathematical formula before pulling the trigger.

    *Precision* is a reflection of the shooter applying fundamental "controls" (to borrow machining terms). Breathing control, loading bipods, foot placement. A good shooter can run a checklist, starting from the tip of his toes to the end of his fingers and top of his head.

    If the controls are not consistent, or not set at the base that the inputs were measured from, your end results will not match the projected performance. For those with a manufacturing background, you can apply SPC to your shooting when you get your numbers.

    When I started getting hazed frequently by my HOG TL, I learned how much math can go into shooting someone and living to tell about it. And that's the first time I wished I hadn't spent all my schooling chasing ass...
    Team Medic, Task Force Zangaro
    "The Cat's Originals"

  2. #12
    Join Date
    Aug 2011
    Location
    E. Tennessee
    Posts
    1,570
    Feedback Score
    6 (100%)
    Excellent post, puts things into perspective, including your best friend's sister!
    Last edited by hotrodder636; 06-30-15 at 22:51.
    ETC (SW/AW), USN (1998-2008)
    CVN-65, USS Enterprise

  3. #13
    Join Date
    Feb 2010
    Location
    AZ
    Posts
    1,064
    Feedback Score
    0
    Great post, I'm especially interested to learn more about shift. This thread has some overlap with an old thread I started. https://www.m4carbine.net/showthread...-ES&highlight=

    Another advantage of using AMR/ATC is that as the number of shots in a group increase, the ATC value becomes closer and closer to the true ATC, without having a bias of being too large or too small.

    However, as the number of shots in a group increase, the Extreme Spread tends to slowly open up more and more.

    I'm a fan of 10 shot groups, because probability will trick you into thinking there is a pattern or correlation when there is not one.

  4. #14
    Join Date
    Oct 2011
    Location
    Alaska
    Posts
    3,311
    Feedback Score
    3 (100%)
    Shift can be measured with a lot of trips to the range. I have a rifle that regularly groups 1" for 5 rounds (honest average of over 100 5 round groups) but the shift on this rifle is horrible. 10 cold bore shots from an uncleaned barrel, shot over 10 days, groups about 4 inches. That's within the kill zone of a moose at 300 yds, so I'm glad this one is my moose rifle.

  5. #15
    Join Date
    Apr 2007
    Location
    FL
    Posts
    9,157
    Feedback Score
    26 (100%)
    Quote Originally Posted by P2000 View Post
    I'm a fan of 10 shot groups, because probability will trick you into thinking there is a pattern or correlation when there is not one.
    In my experience, 5-round groups tend to help reduce shooter error.
    This usually isn't a big deal right out of the gate, but when you get into the 200 round area shooter fatigue becomes more of a thing.
    Still, that 5-round group on its own is a data point, but that data needs to be populated with several (at least 4) groups to accurately indicate anything usable.

    This comes around to zeroing.
    After my initial zero, I won't touch the turrets until I have at least 4 groups from which to determine actual group center.
    If the group center isn't consistent with regard to point of aim, I want to check heat, and will generally shoot 4X 5-round groups, with enough time between strings to allow the barrel to cool.
    If the group centers become more consistent, I do a heat work-up, shooting 40 to 50 rounds in 5-round groups with only enough time between groups to ensure good natural point of aim and correct position/NPA.
    If the group to group dispersion does not improve, I at least know that the issue is probably something other than heat.

    When it comes to data collection, I am more interested in group centers in relation to the POA than I am in individual group size. After shooting the gun for a while, I know what the groups should look like, and anything weird (large) gets noted.
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

  6. #16
    Join Date
    Aug 2011
    Location
    N.E. OH
    Posts
    6,167
    Feedback Score
    0
    Awesome writup. Thanks for your contributions here, and throughout the forum.

    Good point on shooter fatigue as well, I usually limit pistol groups to 5 shot(to check Load precision), and overlap targets to take drift into account (to check accuracy). I need to start saving targets to watch for shift at different environments.

    Thanks for the education!
    Last edited by MegademiC; 07-01-15 at 16:08.

  7. #17
    Join Date
    Apr 2007
    Location
    FL
    Posts
    9,157
    Feedback Score
    26 (100%)
    Added an edit to give my perspective on group population.
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

  8. #18
    Join Date
    Apr 2007
    Location
    FL
    Posts
    9,157
    Feedback Score
    26 (100%)
    Quote Originally Posted by BigLarge View Post
    Are these 5 round groups, and under what time frame? I'd like to know more about what variables will affect shift. Suppressor weight, barrel profile, firing schedule, etc etc...

    Great post, BTW.
    Unfortunately, I can't give that much of a look behind the curtain, but, I can say this:
    Those groups have to be shot by a dude, outside, using only the amount of ammunition provided by the government, and will have to get through upward of 20 in a day.
    Not much time for dallying.
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

  9. #19
    Join Date
    Jun 2011
    Location
    Vegas
    Posts
    6,717
    Feedback Score
    5 (100%)
    Quote Originally Posted by Failure2Stop View Post
    AMR minimizes anomalies, but can be misleading when talking to someone that is thinking in AMR.
    That last bolded AMR should probably be "extreme spread" instead.

  10. #20
    Join Date
    Mar 2011
    Location
    Mid-West, USA
    Posts
    1,750
    Feedback Score
    37 (100%)
    Quote Originally Posted by Failure2Stop View Post
    Still, that 5-round group on its own is a data point, but that data needs to be populated with several (at least 4) groups to accurately indicate anything usable.
    Thanks for this thread. I'll be using the quoted portion from now on. I don't know why I never thought of this before, but it probably explains why I'm always tinkering with my scope when I zero.

Page 2 of 6 FirstFirst 1234 ... LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •