MOA Question on my gap 308 Winchester

Cologgi

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I am not sure what is going on here. I shoot a GA Precision crusader, 308 winchester, 24" barrel. Badger 20 moa base,Nightforce 5.5-22x56 NPR1. My reloads are federal case, 45 grains varget, federal match primers, 178 amax bullets, seated to 2.84. At 880 yards I am holding 12" or less depending on me and the wind. My problem is that I am having to run my scope up to 61 moa.

I do not have a chronograph but I am guessing that my FPS is around 2500fps. My chart and other info that I have seen is saying I should be around 32 or 33 moa.

The scope rail was already mounted when I purchase my rifle. My first thought is that the scope mount is backwards. Could this be the case, am I reading my moa wrong, is my fps way low, or what else is going on.

http://i45.tinypic.com/2vdntx2.jpg

 

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    Re: MOA Question on my gap 308 Winchester

    What scope it is, and have you checked your scope on paper from 0 to at least 40 MOA up at 100 yards insuring it is tracking correctly?

    61 MOA is just plain wrong all around, theres is something else happening here, either operator error or scope error.
     

    shadow4

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    Re: MOA Question on my gap 308 Winchester

    61 MOA from your 100yard zero, or 61 MOA from the very bottom of your scope adjustments?
     

    Cologgi

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    Re: MOA Question on my gap 308 Winchester

    It is zeroed at 100. Holds very nice groups. At 300 it is dialed up to 26 moa. I have not checked the tracking at all. Basically mounted it, zeroed it, and have been dealing with it as it is but am ready to figure out what the deal is.
     

    lowlight

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    Re: MOA Question on my gap 308 Winchester

    Dude, you are completely lost, at 300 yards you should only be using 5 MOA at most.

    Take a picture of your set up, or just get with someone to train you up. This is not right at all...
     

    shadow4

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    Re: MOA Question on my gap 308 Winchester

    Just to make sure we are on the same page here 4 clicks on your scope equals 1MOA. Are you sure you are talking about MOA here or are you counting every click as an MOA. If not then something is wrong.
     

    lowlight

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    Re: MOA Question on my gap 308 Winchester

    He has to be counting clicks, but then again 61/4- 15.5 which wouldn't be for 880 yards, so something else is up on top of possibly counting clicks.
     

    shadow4

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    Re: MOA Question on my gap 308 Winchester

    Well, something is definitely wrong.... Is your scope objective touching your barrel (or objective scope cap). I could not tell from your picture. If it is, it could be bending the scope tube slightly and messing up your adjustments.

    If its not your scope objective touching your barrel, see if you have a buddy that will let you borrow a scope and try it again with another scope.

    Also, maybe just take a 2nd look and make sure none of your scope base screws or scope ring screws came loose (it happens).
     

    Swan

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    Re: MOA Question on my gap 308 Winchester

    Checking the tracking at 100yds (while zeroed @100) would be my first step. That will pretty much tell you the problem, or at least an indication, I would think.
     
    G

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    Re: MOA Question on my gap 308 Winchester

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Angel Eyes</div><div class="ubbcode-body">I am not sure what is going on here. I shoot a GA Precision crusader, 308 winchester, 24" barrel. Badger 20 moa base,Nightforce 5.5-22x56 NPR1. My reloads are federal case, 45 grains varget, federal match primers, 178 amax bullets, seated to 2.84. At 880 yards I am holding 12" or less depending on me and the wind. My problem is that I am having to run my scope up to 61 moa.

    I do not have a chronograph but I am guessing that my FPS is around 2500fps. My chart and other info that I have seen is saying I should be around 32 or 33 moa.

    The scope rail was already mounted when I purchase my rifle. My first thought is that the scope mount is backwards. Could this be the case, am I reading my moa wrong, is my fps way low, or what else is going on.

    http://i45.tinypic.com/2vdntx2.jpg

    </div></div>

    With a 100yd zero, it should only take between 14 to 15.25 MOA at 600 then add 10 more to 800, another 6 to 900, and another 6.5 to 1K.

    Go back an recheck your numbers, as those numbers don't work at all. You sure your not hosing a rev count or three?

    61 MOA gets me pass 1350yds depending on environment.
     
    G

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    Re: MOA Question on my gap 308 Winchester

    Your not counting the total scope hash marks + knob reading w/o subtracting your starting point are you?
     

    Cologgi

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    Re: MOA Question on my gap 308 Winchester

    1zo7ssj.jpg

    iejf2u.jpg


    Here are 2 pics of my last 880 moa setting and of the scope from the side. All mounts and screws are tight.

    The last trip out I took a measuring wheel to verify distance and was right on at 880.

    One other thing. ALl of these groups have been shot with an AAC cyclone but when I added it to my setup it did not change my zero so I ruled it out.

    The only idea I have come up with is that my muzzle velocity is around 1800fps. Is this possible with the load that I am using and the can?

    My groups are very tight and respectable

    I am using the ballistic calculator on my iphone. All caculations are right on with what everyone has been commenting about what the moa should be.
     

    CK_32

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    Re: MOA Question on my gap 308 Winchester

    Yea I'm no scope expert but that seems almost ridiculous.

    Maybe get a hold of the guy you bought it from.. Could be the reason he sold it in the first place....

    At 750 I'm dialing 25 MOA with my 308 26 MOA at most. At 300 Im only at 4 MOA.

    Try to post more pics.

    Also Is this your first rifle? (Scoped rifle)
    Who installed your scope?


    Each Number on your scope..

    nfturretx250.jpg



    Each number is 1 MOA.. Each click/line is 1/4 MOA... So if you turn from 0 to 4. That's about 4 MOA.
     

    Cologgi

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    Re: MOA Question on my gap 308 Winchester

    unless I am mistaken in the pic you can see the elecation knob has been cranked past zeor 6 times and stopped on 3.75 moa. Each horizontal line under the knob is 10 moa

    No this is not my first rifle or scope.
     

    CK_32

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    Re: MOA Question on my gap 308 Winchester

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Angel Eyes</div><div class="ubbcode-body">unless I am mistaken in the pic you can see the elecation knob has been cranked past zeor 6 times and stopped on 3.75 moa. Each horizontal line under the knob is 10 moa

    No this is not my first rifle or scope. </div></div>

    I was just using that knob as an example.. Just making sure your reading your markings correctly.
     

    lowlight

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    Re: MOA Question on my gap 308 Winchester

    Did you actually crank it past 0 six times or are you just counting the lines under?

    You zero doesn't have to be on first line under the knob and probably isn't chances are you are off a revolution and you are not actually returnIng to zero. People go revolutions off all the time because the zero location isn't at the first line?
     

    Cologgi

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    Re: MOA Question on my gap 308 Winchester

    Well, at zero, the knob is cranked down past 0 6 times until it stops. I just checked and all the way cranked down to my zero is just above the 1st horizontal mark.

    I am going out in the morning, I guess I will try the 100 yard zero drill and see where I end up.

    Even if I were off one revolutiom, my scope is still reading double the moa I should be at.
     

    Cologgi

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    Re: MOA Question on my gap 308 Winchester

    it turns 8 moa down from zero or "under zero" till the knob stops turning
     

    gebhardt02

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    Re: MOA Question on my gap 308 Winchester

    So when your rifle is zeroed at 100 yds, you can only then turn your elevation knob down 8 MOA at which point it is physically bottomed out? Can you take a picture of your elevation knob when the rifle is zeroed at 100 yds? There is no way you should need that much elevation to either of those distances, and not likely you would be that close to the bottom of your adjustment range for a 100 yd zero either.

    Geb
     

    CK_32

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    Re: MOA Question on my gap 308 Winchester

    Ok I don't think your getting what were trying to explain..

    When you go back out shooting let your range master take a look at it and explain how it works and he might explain what were trying to say a little better or maybe find the actual problem with it. Going on you get a knowledgeable range master.
     

    shadow4

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    Re: MOA Question on my gap 308 Winchester

    Angel Eyes. Unless your 100 zero is at the very bottom of your scope (highly unlikely), your not dialing up 63MOA+. You need to find out where your 100yard zero falls on your scope and make a note of what "hash mark" is showing. Mine falls on the 3rd "hash mark" on my Nightforce scope. Meaning, my scope already has 3 complete turns on it from the bottom for my 100y zero.

    Go back out, find your 100y zero make a note what hash mark is showing (write is down). THEN count how may full revolutions + how many extra MOA you need to get to 880 yards (take a look at what hash mark is showing again). For every full revolution on your turrets, that will be 10 MOA. The hash marks are only there as a point of reference.
     

    Cologgi

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    Re: MOA Question on my gap 308 Winchester

    zeroed 100, knob off
    rjmsdu.jpg

    zeroed 100,with knob
    2445zjr.jpg

    300 yards, 2 times past zero stopping on 4 (24moa)
    2j65yk3.jpg

    880 yards, 6 times past zero stopping on 4 (64moa)
    2rxxtgj.jpg

    All shots are dead on.

    CK_32, what am I not understanding? I think it must be something with the load.

    I shoot a MK4 on my whisper and have no problems whatsoever with my moa adjustments
     

    DALLAS ROOTS

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    Re: MOA Question on my gap 308 Winchester

    Sounds like a very slow load, get some factory match ammo and re-zero the rifle with it. The factory ammo will have a ball park FPS on the back of the box, run your #'s with that FPS.

    Your #'s sound like my subsonic load.

    If your not using a Chronograph to see what your load is doing than, you really cant blame the scope. Your come up should have been your first clue that your load was off. Run some low FPS #'s on JBM till you find the same come up #'s you are using, you will find your ball park FPS of your load.

    Get rid of those Fed. cases and us WIN. or LAPUA brass.
     

    Goldbeachman

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    Re: MOA Question on my gap 308 Winchester

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Angel Eyes</div><div class="ubbcode-body"> My reloads are federal case, 45 grains varget, federal match primers, 178 amax bullets, seated to 2.84.


    </div></div>

    Maybe take a reloaded round from what you have been shooting. Dump the powder out and weigh it.

    Borrow/buy a chronograph.

    Take scope off, put on another scope and try again. Borrow a scope if you don't have another appropriate one.

    If you haven't solved the problem by then, consider exorcism.

    Good luck!
     

    CK_32

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    Re: MOA Question on my gap 308 Winchester

    Ok i guess you are getting what we were saying. Yea I'd say try a box of factory ammo take her out and see how they do. Then take your loads and re-weigh them.. Then go try using different powders, bullets and primers ect. if thats not the problem. That looks like a load problem more than anything.

    Hand loading is always trial and error so it being your hand loads wouldn't be uncommon. GL.
     

    gliechty

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    Re: MOA Question on my gap 308 Winchester

    I would say that your scope has an erector problem.

    With a 20 moa base, the scope should zero at about 32.5 moa up from bottomed out. It should only take around 30 moa to get to 1000 yards with that load. That would put you around 62.5 moa total from bottomed out. That scope has 105 moa total travel, so that would be roughly centered.

    Either your turret is slipping when moving or the erector is just way off. I vote for the second option.

    The quick and easy thing to do is send the scope to Nightforce. They are very good with CS. And then you will have eliminated the scope as a problem.

    BTW, the load you are running is probably closer to 2700 fps in a custom barrel. I run that load on occasion.
     

    Cologgi

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    Re: MOA Question on my gap 308 Winchester

    Lite Tac, you were right on with the elvation turret slipping. Apparently it slipped quite a bit at some point and I retightend it when doing a routine check. I took some hornady SST to rezero. At what I thought was my original zero I ended up being way off. I rezeroed and it ended up being about 35 or so MOA low. My new zero is right around 35 MOA.

    I used Lowlights advice on the tracking drill after rezero. I shot a 3 shot group at 100, dialed 10 MOA, shot 2, Dialed another 10MOA, shot 2 more, dialed down 10 MOA, shot 2, dialed back down to zero, shot 2. To the tape measure and all three groups were tight and right at 10" appart. I think the repeatability is good to go.

    Upon further inspection my elevation turret has 3 hairline cracks on the sides and a crack on top of the turret. I will be calling Nightforce for a replacement turret tomorrow.

    Thanks for all the good advice and input on this problem. It should not be an issue in the future.

    I thought I would throw in a pic of my final zero group. I was happy with it. 4 shots at 100 yards
    2dtc7k0.jpg