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RIFLE SCOPE ADJUSTMENTS

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 07:15
Hammer6 View Drop Down
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All,
 
Need some feedback on this one...... currently working with a 6-24x42 Adjustable Objective (Mil-dot) Scope mounted on a Mauser Kar 98K (8MM).  The Scope has 1/8th in adjustments which equals out to 8 clicks = 1 inch adjustments @ 100yds.  To Zero the scope @ 100 yds, the Objective lens has to be set to 10 power.
 
when I increase / decrease the objective's power, does that effect the dope (zero) on the gun? If so, how to I compensate?
 
For longer distances, 300, 500, 1000 yds,   How do I dial in the scope to those distances without wasting ammunition? 
 
If 8 clicks will move the strike of the bullet 1 inch @ 100 yds,  how do I figure out bullet strike adjustments at longer ranges?

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 07:58
8shots View Drop Down
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Firstly, to zero the scope it can be set at any power, in my humble opinion. To zero the scope= the bullet prints to within 1inch of the what you were aiming at. That point of impact should not change drastically even if you adjust the scope power.
What you could be referring to is a bullet drop compensator reticule. In other words the scope reticule or crosshair has several horizontal lines. The use of this BDC requires the scope to be set at a fixed power which is specified by the maunufacturer. This could well be 10x as you state.
The center cross will not be effected by the scope magnification, or the zero in other words. That stays center.
The other aim points can grow or shrink as the magnification is turned up or down (2nd focal plane stuff).
You can take a graduated paper target, one with one inch lines on it at set it out at 100yds. Put your center cross on one line. Then see how many (or parts of)inches each next line falls below the center line. For example the center is on one line. The next line is 1.8inches below, the 3rd line 2,4inches below the center line etc. That will give you your MOA for each line. Then, using the buulet drop chart and a computer you can calculate.....
Or you can symply shoot a round or three using each reticule line at 100yds and do the same. It is not a simple thing, but can be done.
I know my rifle shoots 1.8 inches high at 100yds to be dead on at 200yds. My one reticule is also 1,8MOA lower then the center zero. So at 200yds I use the second line and I am spot on.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 08:14
8shots View Drop Down
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If your rifle only has a standard reticule or cross, then the rifle can be zeroed once again at any magnification. By dialling the power up or down the zero should not alter significantly. On a good quality scope it does not alter at all.
The adjustable objective that you refer to symply focusses the reticule at each distance. This is done by looking through the scope and adjusting the Adjustable Objective untill the target can clearly be seen through the scope. This will not change your point of impact, it will only allow you do see your target clearly and parralax free.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 09:45
Hammer6 View Drop Down
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In order to be Parallelax free, the reticle has to be clearly defined in front of the target correct?

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 09:45
Hammer6 View Drop Down
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Parallax free
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 10:21
RifleDude View Drop Down
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Welcome, Hammer!
 
I think you are confusing 2 different things here.  First, the W/E click adjustments for zeroing the rifle are independent of magnification.  Regardless of magnification, every click of the knobs always moves bullet point of impact 1/8 MOA, or roughly 1/8" @ 100 yds.  The parallax adjustment is for focusing the target image so that both the image and the reticle are on the same image plane, thus insuring you don't have apparent reticle shift when you move your eye away from the centerline of the eyepiece.  This helps prevent parallax errors that can affect your shooting precision.  It does not have any mechanical effect on POI.
 
If your scope has a second focal plane reticle, as it sounds like it does, the mil dot spacing is accurate at only 1 magnification, so you would use that magnification for ranging your target using the mil dots.  The dots are placed 1 milliradian apart, which is 36" at 1000 yds or 1 meter at 1000 meters.  Knowing this, you can both estimate distance to your target (if you know the size of the target) and compensate for bullet drop with the reticle.  The formula for determining the range to the target is:  size of target in yds X 1000 / size of target in mils = range in yds.  To arrive at your firing solution, you then either adjust the elevation turret the required number of clicks or use the reticle for holdover.  Of course, you will need to know your bullet drop at various distances with the load you're using, which you can get by either shooting at that distance and recording actual drop or using a ballistic program.  Since the reticle of a second focal plane scope is non-magnifying, or in other words it doesn't increase or decrease in size in direct proportion to the target image as you change magnification as a first focal plane reticle does, the proper mil spacing is only valid on one power setting.  This doesn't mean that you cannot use the mil dots on other powers, you just have to do a little math to compensate for the difference in magnification. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 10:37
Hammer6 View Drop Down
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So the bullet drop is based on the specific load of the bullet?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 10:45
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Mildots are not a bullet drop compensator.  They can be used as that but you need to first develop a load and find out the drop of that bullet at each particular distance then you can start using the mildots as a make shift BDC.  Mildots are really for ranging and then you use your adjustments turrets on your scope to dial in distances. 

Exactly what scope do you have?

To do what you want you really need a target type scope with target turrets that allows you to make adjustments and be able to return them to zero.  If you have just got regular hunting type turrets you are going to have a hard time doing what you want to do.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 10:45
Hammer6 View Drop Down
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is the formula for determining range.......size of target in yds X 1000 / size of target in mils = range in yds....... universal at any range? 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 10:48
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Barska Varmint 6-24x42 Adjustable Objective
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 11:02
Hammer6 View Drop Down
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Rifledude, can you give me examples of range estimation and firing solution? 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 11:02
supertool73 View Drop Down
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Look at it this way.  1 mildot at 100 yards is 3.6 inches.  At 200 yards it will be 7.2 inches, at 300 10.8 at 400 14.4 at 500 18 and so on, at 1000 it is 36 inches.  So just as a very simple example lets say you zero your scope for 100 yards and your particular load just happen to drop 3.6 inches at 200 yards.  that means you could hold half of that first mildot under the cross on your reticle and be right on.  (but you need to be on the power setting on your scope where the mils are true, many times that power setting will be out lined or look different on your power ring. If it is not you need to verify in your manual which power setting it is.) It is very unlikely it will work out like that, more than likely you are going to have to use 1/4 mils to get to your distances.  Hope that makes sense.  Now one MOA at 100 yards 1 inch, at 200 yards 1 MOA is 2 inches and 300 it is 3 inches at 400 it is 4 inches and so on and so on.  Now 1 moa is not exactly an inch but it is close so we will call it an inch for this example.

Now if you have target turrets.  You have zeroed your gun at 100 yards, and you have set your turrets so it is on 0.  At 200 yards lets say your particular bullet will drop 4 inches.  So in order to hit dead on you need to dial your turret up 2 MOA or in your case 16 clicks because each click is 1/8 of an inch/MOA.  Now inches and MOA are not exactly the same but they are close so in this example we will just interchange them.   Now at 500 yards lets say the bullet will drop 60 inches.  So 1 MOA at 500 yards in 5 inches, so if your bullet is dropping 60 inches you will need to dial your scope up 12 MOA or 96 clicks on your scope.  Which equals 60 inches

Hope that makes sense to you.  It is kind of hard to write out.


Edited by supertool73 - February/20/2008 at 13:46
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 11:19
Hammer6 View Drop Down
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It does, thank you.......  For factory loads,  does the manufacturer publish Bullet Drop? or is that up to the individual shooter to compute?

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 11:45
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Here is a ballistic calculator.  http://www.hornady.com/ballistics/ballistics_calculator.php

Some of the manufactures will post ballistics, but really they are pretty general because a round is going to shoot different in each rifle.  Even changing powder lots can change the point of impact of your rounds at given distances.  So it really depends on how accurate you want to be.  If you are shooting deer and elk at longer ranges then the little differences are not going to make that much difference, but if you are shooting at pdogs at 500 or 600 yards it could make a huge difference.
So it is best to find some ammo that you really likes and shoots well in your gun then go buy 1000 rounds or more of it that is from the same lot and then start developing your own ballistic cards for that rifle ammo combo. 
It would also really benefit you to get a Chronograph so you know exactly how fast your bullets are going as well.  Cause some rifles may have a smoother or rougher bore and could cause some pretty dramatic effects in the published speed of that bullet.   With using a chrony and ballistics software then you can find out really close where your bullets will actually hit a given distances then all you have to do is fine tune for each distance.  With out the Chrony and ballistics software you just have to shoot and keep making adjustments until you get everything right.  But if you just want to shot and learn that is a great way to do it.  Personally I like to use the chrony and software and just fine tune and then practice my accuracy.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 11:47
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( I'm afraid all that walking to school in the snow was a waste.....'cause you lost me......I think I'll stick to regular crosshairs and hold the crosshairs up in the sky for shootin' at critters real far away..........)             Bucky                                   
 
( should I sign this one "PYRO" or "Big Squeeze"?)
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 11:53
supertool73 View Drop Down
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Originally posted by Ed Connelly Ed Connelly wrote:

( I'm afraid all that walking to school in the snow was a waste.....'cause you lost me......I think I'll stick to regular crosshairs and hold the crosshairs up in the sky for shootin' at critters real far away..........)             Bucky                                   
 
( should I sign this one "PYRO" or "Big Squeeze"?)


Ed you are to funny,Roll%20on%20Floor%20LaughingI'm sure glad you are on this forum, you keep us all laughing.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 11:54
Hammer6 View Drop Down
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Do you have an example of a Ballistics Card?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 12:16
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Hammer, for basic instructions on mil dot use, I recommend you buy a "Mil Dot Master," which is available for sale on this site. 
 
Supertool is correct in saying that the mil dot is really not a ballistic compensating reticle in that it was designed for determining distance to a target.  However, it can be used as such, IF you know your actual drops at various distances. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 12:59
supertool73 View Drop Down
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Here are some cards you can order from Brownells.  http://www.brownells.com/aspx/NS/Store/ProductDetail.aspx?p=19636

Really you can make them on a index card.  you just need to fill in distances and adjustments MOAs for that distance. 

If you want to get a little more techinical you could get some software that would print you data for you.  http://home.comcast.net/~jesse99/hunting.html
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/20/2008 at 13:00
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Thanks

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/21/2008 at 02:11
8shots View Drop Down
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Thanks Supertool, for stepping in the breach there. I also walked to school in the snow. If I recall it was uphill going to school and uphill coming back home again. Life was tough and we did not have 'puters and ballistic charts and such.
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