How important is an adjustable objective?

Discussion in 'Long Range Hunting & Shooting' started by 7mmAI, May 15, 2008.

  1. 7mmAI

    7mmAI Active Member

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    I will be going on a Utah LE bull elk rifle hunt this fall. I know I'm darn lucky to have drawn the tag and that is why I want to do everything I can to prepare.
    My question is how important is it to have and adjustable objective for elk hunting out to 700 yards? I have a 338 win mag with a leupold 2.5-8x, it shootsgood but not great yet about 1". I also have a 30-06 that shoots very well Accumark, it shoots 168 gr barnes tsx bt 3020 fps as good as I can shoot and 180 accubond very well also.
    How much better would I be likely to shoot at 500-700 yards with 16x top end and adj. obj. compared to 8-10x top end and no adj obj? Thanks for any help.
    Ps I already have a 4200 elite 4-16 x40 and am thinking about the elite 6500 scope also.
     
  2. tjonh2001

    tjonh2001 Well-Known Member

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    you wont be able to be accurate with eather gun out to those ranges without an adjustable objective or a side focus. you need those to take the parallaxal out of the scope.when you look through your scope at a target past about 400. leupold sets there scopes to 150 yards at the factory. the crosshairs move when you arnt moving the rifle.

    -set you gun up on a target so it doesnt move
    -lift your head of the cheek piece
    -look through your scope and move your head around
    -you will see the crosshairs move without moving the gun

    if you have an adjustment you can get it so you dont have any crosshair movement.
     

  3. Bravo 4

    Bravo 4 Well-Known Member

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    Sounds like you have never shot at those distances before. I think your equipment is up to the task. Last year I used a Leupold MK 4 3-9 MRT and wouldn't have have hesitated to take a shot at that range, and my targets were quite a bit smaller then an elk. I have never hunted elk but have seen them and they are pretty darn big. Find something the size of an elk, maybe a horse, and set up 700 yards out and look at it through your scope. If you don't think you have enough power then you should change out your scope, but it just sounds to me like you need to go out and shoot....A LOT!
     
  4. 7mmAI

    7mmAI Active Member

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    I have shoot a lot at 200, 300 and a little 400 yard distances but very little past 400. How much do suppose the crosshairs move at 500 yards with no adjustable objective? Thanks for the feedback on the need for an adjustable objective. I have a friend that has a 300 dakota with a leupold 3.5-10x and no adj abj. he has shot goo groups out to 600 and killed a few deer 500+. so I was just wondering if it was a good idea at my hunting distances of 500-700. Thanks Dean
     
  5. Bravo 4

    Bravo 4 Well-Known Member

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    From what I have always been told, taught, and seen you shouldn't worry about parallax until your mag gets over 10X.
     
  6. Buffalobob

    Buffalobob Writers Guild

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    The forum is divided up into many sections. This is the "Hunting" section.


    Down in the foru m section on "Rifles, Equipment, Optics etc " is an Optics section. In the Optics section is stuff on Optics. In the Optics section there one sticky and only one sticky, and I will give you three guesses as to what the stickey is about. If you are unable to guess correctly the subject of that stickey then perhaps someone will come along and give you a hint.

    I have personally read that stickey about four times.
     
  7. 7mmAI

    7mmAI Active Member

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    I debated on putting this in the optics section, but I was interested in what hunters thought more than long range target shooters so it ended up here.
    Great link it explains the optics very well. Thanks BuffBob.
    I didnt see that it answered my question of how far parallax could shift the image by not being centered in the scope of lets say a 10x scope, parallax set at the factory for 150 yards. The article talked about increasing with magnification, distance and how far off the 2 image planes are. But didnt seem to make it easy to figure out. Just wondering if anyone has a real world guestimate. Thanks, Dean
     
  8. Buffalobob

    Buffalobob Writers Guild

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    Here are the three things you need to know from the sticky.

    1. Extreme error due to parallax is about +or - 1MOA due to eye misalignment. My personal experience is that 0.5 MOA is pretty common with a sporter rifle where the stock is not perfectly fitted to the shooter and the scope.

    2. Parallax gets worse at higher magnification. Elk are likely to appear when you are not able to get into a benchrest position and have to shoot with a less than perfect stockweld. If you do not have adjustable parallax then you are introducing a lot of error into your shot (0.5 MOA )on top of bad shooting position and bad wind estimate and bad range estimate and poor bipod placement. So by spending a little money you can eliminate 0.5MOA of error from the list of errors that may occur. That is what parallax adjustment does for you- gives you one less excuse for missing.

    3. Catshooter laid out the steps to set up a new scope. Like all of us he has his peculiar personality but he is one of the most knowledgeable people around when it comes to optics. Do yourself a favor and print it out and follow it meticulously when you get your new scope.

    Finally, B4 gave you some very very good advice about the need to practice.
     
  9. 4xforfun

    4xforfun Well-Known Member

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    Just a thought to those of you who say that paralex only becomes a problem above X power. Now, I am not arguing with you, but....my belief is that there is just as much paralex at 4x as 32x. It's just not nearly as noticeable at lower powers. If you have 3/4 MOA deflection at 32x, there is 3/4 MOA at 4X also. It's just harder to decipher a 3/4 MOA deflection at 4X at XXX yards. I have done some "tests" (for a lack of a better term) with the target having lines every 1/2 moa. I purposely set my paralex out of wack and did the "move the head around to the edge of the FOV" thing at 32, 24, 16, and 8x. From what I could tell it was all the same. Just not as noticeable at the lower powers. One thing is clear though. As far as focus only (not paralex), the target is a lot clearer at the lower powers. But, I also noticed that no matter what power scope you use, that is the case. A 3.5 - 10 will be a clearer at 3.5 power, but so will a 12-42 be clearer at 12 power.
    I could be wrong (again), but that is what my limited test showed me. And it isn't very scientific.
     
  10. silvertip-co

    silvertip-co Well-Known Member

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    Personally I hate AO. But over 10x is sort of a necessary evil (physics of light). The new sidewider scopes seem like a good compromiste to that huge knob hanging off the front of a big scope.
     
  11. NONYA

    NONYA Banned

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    I prefer and now use non adj pars on my scopes,my accuracy out to 1000 yard targets didnt change at all after switching to fixed power 10x non adj scopes.
     
  12. silvertip-co

    silvertip-co Well-Known Member

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    I actually thot about getting a Weaver T-10 for my long range hunting rifle since I have been thinking for a while that over 10x is just a lot of bother for not much value received. Maybe thats why US mil scopes are 10x or less. I dont anticipate any 1500 yd kill shots any way. And these 15-50 x 60 scopes scare me. I mean what does one DO with that much magnification???
     
  13. edge

    edge Well-Known Member

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    If you set up the scope correctly, at maximum magnification and at infinity, don't all other settings become less prone to Parallax?

    edge.
     
  14. 4xforfun

    4xforfun Well-Known Member

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    Shoot very, very small groups at 1000 yds plus!!:D