MOA at 400 but can't get on target at 650?

Discussion in 'Long Range Hunting & Shooting' started by Tommy1984, Sep 19, 2019.


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  1. greenejc

    greenejc Well-Known Member

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    You can build a portable long range target with a used bed sheet and a couple of aluminum 6 foot stakes. You build pockets on each end of the sheet and stretch the sheet between the stakes, then drive the stakes into the ground. Then glue butcher paper to the sheet to get a stiffening. Spray a large orange or black dot in the center, and you can then tell what your rifle is actually doing at various distances. Also, follow eric1115's advice and get a steady, solid rest as a firing position. Sandbag both the stock in front of the action and the buttstock in. The only things touching the rifle should be the sandbags, your shooting hand, your cheek and your shoulder(place your non-firing arm on the rest or ground and place your non-firing hand at the buttstock to help steady it on the sandbag: don't use that hand for supporting the stock, just as a steadying help-let the sandbag support the weight of the buttstock). Make sure your elbow is rested. If you have a good rest, your crosshairs shouldn't move at all except with your heart beat. (natural point of aim):You should be able to look through your scope and have it centered on the target, and then close your eyes and open them and still be within 1 moa of center on the target with your crosshairs (actually, it should be less than about 0.5moa). Fire two 5 round groups at 400 yards as a base of accuracy, then move the target at 50 yard increments and do the same thing. This will tell you if its the rifle, the loads or you. It will also give you data on actual bullet drop at various distances with your rifle at your altitude. You'll want to keep a data book with that information for future reference. Keep in mind that this will give you data for that load only. If you want exact data for another bullet/load, you'll have to do it again. But you will have a baseline to work from and it will not require more than maybe adjusting at 400yards and 600 yards.
     
  2. freddiej

    freddiej Well-Known Member

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    What I am about to suggest I do with great hesitation due to the company I am in and there are so many that disagree with me on this. I had this happen to me while I was shooting 1,000 competitions in California. My rifle was a 1:10" and I started out with 200 and 210 grain slugs with somewhat the same results as you are having but at a bit different ranges. between 600 and 700 yards my groups started opening up with 210 grain slugs, between 800 and 900 yards the 200 grain slugs opened up their groups. this phenomenon is called marginal stabilization. as the slug slows down so does the rotation, when you see a dramatic opening of your groups from one yardage to another your slug is going through a decay of stabilization. normally a 1:10" barrel should stabilize a 180 grain slug out to 1,400 to 1,700 depending on the AOL of the slug. Berger VLD's ruined all that very quickly. the longer the slug the faster the twist needs to be. where the cutoff is for a 1:10" twist ends its stabilizing of a particular slug and the need for a 1:8" twist barrel has changed over the years. from what you are saying your slugs are not stabilizing at or near 600 yards. this can be two reasons. rotational velocity is not fast enough keep the slug stable, or your FPS and your rotation are too slow to ever keep it stable out past 500 yards. I would try a 175 grain Nosler Accu-Bond and run the same 400 and 650 yard shooting. if your gun shoots true at 650 then your gun needs a lighter slug or a faster twist barrel.
     
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  3. Wedgy

    Wedgy Well-Known Member

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    Stainless stalker comes with a 10 twist barrel so the 180's are plenty stabilized. I think it is as simple as a hot pencil thin barrel, OP said he put a string of 10 rounds thru it then stretched it out to 650 yards. It's a 6.5 lb gun so we know the barrel can't fire a string. There isn't 3 feet of parallax going on either, OP said conditions were calm so it's not wind, and the misses were all around the target. I've see a dozen Cabela's disaster scope jobs so that's worth checking too. The barrel is too hot and/or something's loose, shooter form. Have you ever shot any gun to 650 before ?
     
  4. John 264

    John 264 Well-Known Member

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    Carbon wrapped barrels are worse they hold more heat than steel barrels
     
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  5. Sam Summey

    Sam Summey Active Member

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    Mar 16, 2019
    I shoot 223 Rem 300 to 600 yds It takes 11 minutes to go from 300 to 600 with no wind. Are you lifting your head when the rifle fires? This may be because you are too anxious to see results. More follow through.
     
  6. Zymurgist

    Zymurgist Well-Known Member

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    Nov 14, 2013
    Tommy,

    Carbon barrels heat up very quickly and cool very slowly. High temperature can effect the repeatability of your shot placement just as you describe.

    Many shooters of carbon barrels will wait a few minutes between shots. Some even cool the barrel between shots by blowing air through the bore or running a wet patch through it.

    There are many posts on this site discussing this issue.
     
    Sam Summey likes this.
  7. lyle2231

    lyle2231 Member

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    Jan 26, 2014
    Try this...Zero @ 100 yes. Use normal come ups to 600 yds 17 minutes. If your scope is 1/4 minute that's 68 clicks. Add another 2 or 3 clicks for the 50 yds added. If that don't do it look to ammo. HTH LYLE
     
  8. Daves762

    Daves762 Well-Known Member

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    I was pushing 210 gr. Berger VLD's out of my 300 WSM. Getting one hole groups at 100yds I set out to longer ranges. At 700 yds I wasn't even hitting a sheet of plywood, let alone the paper target stapled to it. My only guess is that they destabilized along the way and tumbled. I switched bullets and have never had that problem again. I did note that the plastic tips on my other bullets melt and ruin my shots past 800yds. Hornady did some great research on this problem. Then developed heat resistant tips to prevent melting. Perhaps the tips are melting?
     
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  9. lyle2231

    lyle2231 Member

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    Sierra can give you velocities for different weight bullets at different ranges. I found some twist rate barrells don't like heavy bullets.
     
  10. John Klingenberg

    John Klingenberg Well-Known Member

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    Nov 13, 2018
    Light barrel and stock off a bipod = a lot of bounce. Bag it. Extreme Spreads and the longer you wait to fire that next round while it sits in a hot chamber changes the ignition chatacteristics as well. So many possibilities. The thing about shooting long range is you have to learn how to do everything yourself. You cant always depend on factory ammo, you cant depend on someone to put a scope on perfectly level, the older chronos are not super accurate based on todays standards either. A couple rounds arent sufficient either. I only put my averages in after at least ten rounds.
     
  11. Stgraves260

    Stgraves260 Well-Known Member

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    The best advice I can give is set you up a huge target like 4’ tall and 3’ wide. Just something big you know you can hit easy. One you know you can hit. You are trying to validate your range finder. The FPS that you have in your rangefinder May not match your chronograph. Face True North when doing this. I can not stress enough on how important it is to validate your rangefinder shooting true north. I used a 4’ x 4’ pieces of plywood. I put a 3 “ shoot and see sticker on the piece of wood. Use what you like. It’s just what I did. Here is some info to help you out with the math. If your adjustments in your scope are .25 MOA @ 100 yards know that at 600 yards every click will move your bullets impact 1.5”. Fire 1 round and go down to your target and see if you hit it. If you did use a ruler and measure how many inches you are Hight or low from the bullseye. Don’t worry about wind yet. Just elevation. So if your bullet impact is say 6” low you will add 1 MOA or 4 clicks. This method will save you a ton of frustration and a bit of money too. Now once you have your bullet impacts on the bullseye. Adjust your FPS in your rangefinder till it matches your elevation turret on your scope. Don’t forget your BR2 Rangefinder is all ready calculating air pressure and your angle/cosine ( up and down hill. ) that is why the above method works so well.
     
    Last edited: Sep 20, 2019
  12. Tommy1984

    Tommy1984 Member

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    Sep 19, 2019
    Ok back to the range this evening. I didn’t have time to stretch it out but I did validate that I was still on at 100 yards.

    Also shot 3 different type of ammo, ballistic silver tip shot 2 moa, Barnes ttsx shot 2 moa however the accubond shot 0.5 moa, I’ll attach a pic below of one of my 3 shot groups with the accubond.

    Next trip will be going back out to long range and trying to figure out what the heck is going wrong.

    Ignore the group up high, that was Barnes.
     

    Attached Files:

  13. msmith57

    msmith57 Member

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    check your scope cross hairs are they loose? lay your scope sideways and tap on it while watching the cross hairs.
     
  14. Bill Cauley Jr

    Bill Cauley Jr Well-Known Member

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    Sep 6, 2018
    Did you just use the data the BR 2500 gave you from 400?at that distance you may have to adjust your BC or velocity to make it correspond to actual data at 650 I have the BR2 the older model and it works great once I have Trued my data out to 1250 while a lot of distances may not be exact they are within one click but I do adjust BC and velocity and look at the whole range of distances and make them all work the best I can, shoot at various distances as far out as you can write down the actual elevation and then adjust accordingly to make it work properly