Bullet stabilization...

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by TireurDelite, May 14, 2005.

  1. TireurDelite

    TireurDelite Active Member

    Messages:
    33
    Joined:
    Feb 9, 2004
    Hello all,

    It has always been my understanding that the bullet is stabilized or close to it when it leaves the barrel.
    This old boy at the gunshop I used to shop told me the reason I am getting good group(for me) at 100 yards and not at 200 is that the bullet has not stabilized. This doesn't make sense. Is he full of it or am I just ignorant?
    Help please!!!
    Thanks for your time.
     
  2. winmagman

    winmagman Well-Known Member

    Messages:
    1,379
    Joined:
    Mar 13, 2003
    TD
    I'm by no means an expert here, but I beleive I have read about the longer heavier bullets(VLD ULD type) taking a couple of hundred yards to "settle down" so you could have so-so groups at 100yds and at 300 yds things tighten up.

    I don't know for sure about the other way around unless your bullet was just barely stabilized at 100, but even then I wouldn't think it would slow enough in another 100yds to make a difference.

    What bullet? Which caliber? What twist?

    Chris
     
  3. James Jones

    James Jones Well-Known Member

    Messages:
    2,854
    Joined:
    Jul 1, 2002
    No to sound like a smart ass but your generaly gonna get better groups at 100yds than 200yds because 200yds is 100yds farther away , unless you just had your numbers backwards.
    Like the man said some guns shooting realy long bullets take a couple hundred yards to flatten out or some guys say "go to sleep" I had buddy that shot a 1-12 twist 30-06 with 175gr Berger VLD's and it would groupe better at 200yds than at 100yds and in dead calm wind would group the same at 300 as it did at 200 , a fellow long range shooter said that the twist was on the line of being two slow for those bullets at it just took a little longer for the air to straiten out the bullet.
    I have two 308's that group right at 1/2moa at 100yds and under 3/4moa at 200yds which basicaly is grouping better at the 200yd mark than 100 not sure why but they both do it with all weight bullets
     
  4. daveosok

    daveosok Guest

    I have heard the term "go to sleep" used a lot in this shooting area.
    While I wasn’t sure what exactly it meant I did witness it and now understand what it means.
    My big gun shoots 3/4 groups (10 round groups) at 100 yards.
    At 400 yards it shoots 1.7 in groups. Now mathematically .75 at 100 yards it’s 1.5 at 200, 2.25@300, 3@400 yards (angular measurement i.e. mil or moa). The bullet has gone to sleep somewhere from 100 yards to 400 yards and thus the mathematical theory disproves itself (concerning the group size) therefore suggesting the "bullet has gone to sleep" otherwise group size should follow mathematical size.
    The mathematical measurement of angular difference over a known distance is always exact i.e. 1 moa is 1.047 @ 100 yards, conversely 1 moa @ 1000 yards is 10.47, however for example only, if your gun shoots 1 inch groups at 100 yards it may shoot 4 to 6 inch groups at 1000 yards.
    This contradicts the mathematical absolutes and only one answer is obtainable; the bullet has stabilized somewhere throughout the range. Since the bullet is the only variable in this equation it must be the bullet. After leaving the muzzle (other than weather conditions) stabilization dynamics are the only true variable to which mathematical equations obtain stabilization characteristics, BC and all the other “known’s” also enter into an equation for trajectory (this does not suggest accuracy only flight path). Stabilization happens at a certain velocity and spin rate, while the velocity decrease over time and distance spin rate decreases much slower even so slow that it really doesn’t matter and can hardly be measured for accuracy estimates. It does seem though that stabilization and trajectory share some common ground but at what point in the bullets path do they connect must only be witnessed in the field where math and reality conflict each other as true data is gathered in real time and not theorized.
    What this is all saying in laymen’s terms is, once the bullet “falls asleep” you can count on it being more accurate than in its state before stabilization.
     
  5. Jon A

    Jon A Well-Known Member

    Messages:
    1,092
    Joined:
    Dec 28, 2001
    I think the guy at the gunshop is confused. I don't see how any of this could cause groups to get bigger at 200 than 100 MOA-wise. There are lots of other things that could, of course.

    Most obviously--were you shooting on a windy day? Depending upon your load, wind drift can be around four times as much at 200 than at 100.

    What scope are you using? If non-adjustable, I'd check it for paralax at 100 and 200--you might find you have more at 200.

    Just a couple obvious things to check....