2" x 12" groups?

Discussion in 'Long Range Hunting & Shooting' started by redneckclimbing, Aug 23, 2012.

  1. redneckclimbing

    redneckclimbing Well-Known Member

    Messages:
    240
    Joined:
    Jan 24, 2012
    So I am developing a round for a friend's 7mm RUM. Worked some loads up at 200 yds. shooting well around 89 and 91 grains of Retumbo 180 Berger HVLD. COAL 3.650.

    I just did two rounds of each the first time, this time I made four of each .5 grains in each direction of these.

    I am shooting with a bi-pod on the front and a rear bag. The scope is a 3X9 and has no parallax adjustment. I know this is not ideal but it should not be as bad as it was I don't think.

    Shot the loads at 400 yds. today to alleviate some of the parallax issue. Was taking my time dry firing between shots to keep myself from flinching. I used two of the 88.5 gr. loads to get on paper at 400 (they were both short) then the next two fell about 1.5" apart at about 10 and 4.

    The rest of the loads had good vertical spreads ( about 1.5") but would be spread from one end of the paper to the other (about 12"). The wind was blowing full value at about 5-7 and we were watching the mirage pretty close so I expected better.

    My question is, is the barrel just grouping them like this or am I doing something else really wrong? (aka trigger pull)

    My next step is to obviously shoot some more 88.5 gr. loads, which I will try to do later this week. But in the mean time any suggestions would be greatly appreciated.
     
  2. Coyboy

    Coyboy Well-Known Member

    Messages:
    2,132
    Joined:
    Jan 30, 2005
    if you had 1/2 moa vertical at 400 and 3 moa horizontal it was most likely one of 2 things.
    Your lack of wind reading or a gun handling issue. Try a rabbit ear bag with a heavy fill so it really holds the back of the gun from moving side to side, don't forget to remove the rear stud.
     

  3. angus-5024

    angus-5024 Well-Known Member

    Messages:
    1,132
    Joined:
    Jan 22, 2008
    Also chech your Natural Point of Aim. Once your on target, all ready to pull the trigger, take your finger off the trigger and close your eyes for 5 seconds. see where you are on the target. If your off the bull, reposition and try again until your smack on the bull.

    I doubt that your getting your but kicked that bad at 400 yards by a 5-7MPH wind. also, do you have a scope level? If your canted it can throw you badly, but usually you will have vertical stringing also.

    Make sure that your not muscleing the gun, especially in your grip. you can be pretty sloppy and get away with alot, but haveing a super flexed grip will through you every time.

    Also check your bi-pod. If its not secure you can have issues.

    could you have someone else shoot it to compare?
     
  4. Bullet bumper

    Bullet bumper Well-Known Member

    Messages:
    1,042
    Joined:
    May 20, 2009
    Are you using a bi-pod?
     
  5. RMulhern

    RMulhern Well-Known Member

    Messages:
    796
    Joined:
    Jan 2, 2003
    "I am shooting with a bi-pod"
     
  6. Bullet bumper

    Bullet bumper Well-Known Member

    Messages:
    1,042
    Joined:
    May 20, 2009
    OK this is typical bi-pod grouping that comes about with poor recoil control and poor grip and butt control of the gun. The bi-pod will skate around from side to side under recoil . The vertical will be fine but the horizontal not so good. You are shooting a 7m RUM not a 6mmBR so you have to hold it firm otherwise recoil will push you and the the bi-pod all over the place .
    Make sure you load your bi-pod by pushing it forward slightly after each shot especially if shooting from the dirt .
    Make sure the butt is in your shoulder and not going under slightly with recoil , which helps the bi-pod skate . The latest sniper technique of laying very straight behind the gun is prone to poor holding if you are not young fit and agile so don't use it .
    Make sure the bi-pod connection to the stock forend is as rigid as you can get as some tend to be not so rigid and flex about from side to side under recoil making horizontal even worse and helping the bi-pod skate from side to side.
    Heavy guns with heavy recoil need much more than a bi-pod attached to a single sling stud it just is not rigid enough.
    Recent experiments I have done with an 18 pound alloy chassis rifle and a Harris bi-pod have confirmed these issues . Some other brands like Atlas are a bit better I feel. In the end I had to epoxy resin the American defence rail adapter to the bi-pod permanantly to stop sidways flexing . Not the rail adapters fault but the single point pull of the Harris bi-pod is just not rigid enough and can rock about around that single point .
    A bit of wind is in there also to one side I reckon but if the group is pread left and right of the center then it can't be all wind , bi-pods are great at controlling verticle but need help to control horizontal .
     
  7. redneckclimbing

    redneckclimbing Well-Known Member

    Messages:
    240
    Joined:
    Jan 24, 2012
    Sounds like we're all in agreance here. It's probably not the load, I just can't shoot!:D I will try some of these things and let you guys know. Thanks for the input!
     
  8. Bullet bumper

    Bullet bumper Well-Known Member

    Messages:
    1,042
    Joined:
    May 20, 2009
    Sure you can shoot . it's just that bi-pod shooting is different from other forms of shooting and it takes a bit of time to work with a new setup .
    Every time I buy a new gun which is not often I find I have to work out all over again how it likes to be shot . Some guns do break the rules so you do have to try different things .
     
  9. redneckclimbing

    redneckclimbing Well-Known Member

    Messages:
    240
    Joined:
    Jan 24, 2012
    Just for future reference, would a muzzle break help this out? Lessening the recoil that would need controling?
     
  10. Bullet bumper

    Bullet bumper Well-Known Member

    Messages:
    1,042
    Joined:
    May 20, 2009
    It can help . What I have found is that the muzzle break tends to lessen the sideways skating potential of a bi-pod because of the left and right passage of gas pressure . Where before it was straight out to the front. Reducing recoil movement can also help .
    However the break can cause other potential issues like more muzzle blast at you and sometimes they throw up sand and dirt at your partner or spotting scope.
    Also sometimes a muzzle break will negativley affect accuracy negating some of the advantage . Sometimes not . It is impossible to say as there is many different designs in muzzle breaks and not that much science behind choosing them.
    I reckon you should try to get along without a muzzle break if you can and just develope the tight shooting style you need to close up the horizontal.
    If that don't work then you could look at other options , like reworking the load , checking the gun for accuracy issues and getting a break.
    However if the recoil is really punishing you then it's a personal choice and in that case it may well do the trick . You can't be sure untill you fit one .
     
  11. WildRose

    WildRose Well-Known Member

    Messages:
    8,210
    Joined:
    Feb 3, 2011
    With that much left to right spread I'm going to lean towards the problem being one or some combination of the following.

    Busted/loosely mounted scope.

    Poor bedding/floating, improperly torqued action mounting bolts/screws.

    Flinching/recoil anticipation.

    Inconsistent mounting/cheek weld.

    With the wind only varying 2mph it shouldn't create anywhere near that much variation at that range.
     
  12. WildRose

    WildRose Well-Known Member

    Messages:
    8,210
    Joined:
    Feb 3, 2011
    Naa sometimes we can all shoot and sometimes we can't hit a bull in the ass at six feet and can't figure out why.

    That's why it's so night to have so many experienced guys here to bounce Ideas off of.

    I can guarantee you there's pretty much nothing that can happen from 0-1,000yds that someone here can't help you figure out and in most cases you'll get essentially the same help from a half dozen of us.

    Nobody figures out all this stuff their first few trips to the field or shooting range and most of us here have spent 30 years or more shooting long range in various disciplines.

    This is what makes this site such a huge benefit to the shooting community on the whole.

    You'll see very little personal horn tooting here and a whole lot of "How can I help".gun)
     
  13. joseph

    joseph Well-Known Member

    Messages:
    1,238
    Joined:
    Jul 26, 2009
    Try this: Just for chuckles put down pressure on your scope with your hand when shooting with the bipod. You may see a big change in your group size. I have seen quite a few rifles shoot a much smaller and rounder group using this trick. If this works then you need to figure out how to change the position of where the bipod needs to be moved. (closer towards the trigger or closer to the muzzle). Also sometimes your load development can also help.

    gun) - - - - - - - - - - - - - - - - - -

    joseph
     
  14. redneckclimbing

    redneckclimbing Well-Known Member

    Messages:
    240
    Joined:
    Jan 24, 2012
    All right, not the same gun but got out today and shot some through my brother in laws .243 Win. that I'm taking on a Mountian Goat hunt on the 4th (Can't Wait!!) I noticed that I defenitely did not have the bipod tight enough on the 7 RUM so when I switched it over I cranked it down really good, seemed to help. Also I made a rear "bag", if you will, with a 2x4 (I will get a pic. up when I get home) so that it has some "ears". This also helped alot. The load we settled on was 44.7 grns. of IMR 4350 under the 95 gr. Berger.

    For a factory rifle it shot pretty well I thought. At 400 yds. I had 1.75 vertical and 3 horizontal. This time the wind was really bad though, gusting from 5-10 and changing directions quite a bit. I noticed with the new "bag" that I could spot my own shots pretty easily, even at 400, which defenitely wasn't happening with the RUM and the other bag I was using.

    I hope tmw or the next day to get the RUM out again and shoot it with a tight bi-pod and the new "bag" to see if that helps that rifle as well.

    Well said by the way, "Not alot of horn tooting and alot of guys saying "How can I help" I am pretty new to the sight still but have learned a ton and have to say that it's nice to have a place to bounce ideas off of others. Thanks again!