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Scope Adjusting |
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stryker86442
Optics GrassHopper Joined: February/11/2011 Location: Arizona Status: Offline Points: 10 |
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Posted: February/11/2011 at 16:30 |
Ok, i'm new to this forum cause I have a question about my scope adjusting. For the most part, I understand how to boresight and zero my scope but I'm new to this and I've hit a snag...i think. I use a paper target at 25 yards to boresight my rifle. When I am finished boresighting, I take my rifle and aim at a 100 yard target. Now, if your sighted at 25 yards and aim at a 100 yard target, the picture in the bore should be lower than my point of aim correct? When I look through my bore at 100 yds when the rifle is sighted for 25, the picture in the bore is ABOVE my point of aim. This is where i'm confused, I'm not sure if i'm just looking to far into it. The way I understand it is, if your sighted at 25 and want to should 100, you have to hold the crosshair over the target to compensate for distance. If you want to shoot closer than where your sighted, you have to hold the crosshair below the target to compensate for shorter distance right?..... Please help.
If anybody could help me I would really appreciate it.
Thanks fellers
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308 Sav
Optics Journeyman Joined: July/18/2010 Location: Kentucky Status: Offline Points: 362 |
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This is assuming you are shooting a center fire cartridge.
Do this bore site in at 25 yards by looking through the bore. Now shoot the 25 yard target. If you are within 1 inch of center on the 25 yard target go ahead and move out to 100 yards and zero your scope. If not go to the next step. Adjust your scope to be about 1/2 inch to 1 inch low and centered left to right. Remember to move 1 inch at 25 yards it takes 4 times the adjustments on your scope's knobs. When getting this rough 25 yard zero I usually adjust the knobs after just 1 shot and not a 3 shot group to get close. Now that you are close to center and an inch low at 25 yards start shooting at 100 yards with 3 shot groups before adjusting the scope for correction. You should be very close. Edited by 308 Sav - February/11/2011 at 17:48 |
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Gerald Baker
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supertool73
Optics God Superstool Joined: January/03/2008 Status: Offline Points: 11814 |
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If you are sighted in at 100 yards then when you shoot close you will actually need to aim high to compensate for the distance of the centerline of your bore to the centerline of your scope.
Just as a quick reference. Say you are using an AR-15, your scope is 3.5 inches above the bore and zeroed at 100 yards. To get that zero your bullet is going to be traveling up in relation to the line of sight until it crosses your line of sight at 100 yards and goes above. So if you are shooting close range say 15 yards then your bullet has not yet had enough travel time to get up into your line of sight. So your bullet will hit low from where you are aiming. So at that 15 yards, you will want to aim 3 or so inches high to compensate the difference between the bullet path and your line of sight. So back to your sight in. Figure out how far above your center bore the centerline of your scope is. Than at 25 yards, you will want your point of aim to be a little bit less than that amount above where you point of impact will be. So say your scope is 2 inches above the bore. Then you want your crosshairs to be about 1.5 inches above where you bullet is actually impacting. That will put you much closer at 100 yards. Personally I don't bother sighting in at 25 yards at all. I bore sight at the distance I plan to zero and avoid all this. Hope that makes sense. Edited by supertool73 - February/11/2011 at 17:42 |
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308 Sav
Optics Journeyman Joined: July/18/2010 Location: Kentucky Status: Offline Points: 362 |
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Ok I should have read your question better. It depends on the distance you are zeroed at and the distance you are shooting at. It also depends on how fast or slow you bullet travels. Think of it this way when you shoot a bullet you are lobing an object at a target a distance away. Because your scope is above the bore that bullet will almost always go above your Point of Aim and back down to your target. that is why you actually have 2 zeros one close and one at a distance. So it depends how close that close range is. For example your 100 yard zero might also be your 65 yard zero. Everything you shoot from 0 to 65 yards the bullet would be below your point of aim. 65 yards to 99 yards your bullet would hit above your point of aim. Everything beyond 100 yards your bullet would hit below your point of aim. So in essence you would aim high from 0 to 65 yards Aim a little low from 65 to 99 yards Aim high from 101 to infinity lol. For all practical purposes that 65 to 99 yards can be ignored except on very slow rounds. But the bullet path is not in a straight line with your bore sight because the bullet is dropping as it leaves the barrel a lot more than people realize.
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Gerald Baker
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SVT_Tactical
MODERATOR Chief Sackscratch Joined: December/17/2009 Location: NorthCackalacky Status: Offline Points: 31233 |
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there use to be a reallly good diagram of this somewhere on here. I will try to dig it up
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stryker86442
Optics GrassHopper Joined: February/11/2011 Location: Arizona Status: Offline Points: 10 |
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Thanks for clearing this up for me guys, it has helped alot. Does anybody know of a good place to find the right adjustment in MOA for different distances? For example, if I'm shooting 150 gr FMJ from a 308 at 400 yds and Im zeroed at 100, how many MOA in adjustment would I need to be on target?
Thanks
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M7025-06
Optics Apprentice Joined: January/21/2010 Location: Nebraska Status: Offline Points: 271 |
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There's a ballistics calculator posted in the Reloading section of the forum. It's for Winchester ammo only otherwise you can find a bunch online. Edited by M7025-06 - February/12/2011 at 21:12 |
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308 Sav
Optics Journeyman Joined: July/18/2010 Location: Kentucky Status: Offline Points: 362 |
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Gerald Baker
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308 Sav
Optics Journeyman Joined: July/18/2010 Location: Kentucky Status: Offline Points: 362 |
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Gerald Baker
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stryker86442
Optics GrassHopper Joined: February/11/2011 Location: Arizona Status: Offline Points: 10 |
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I see that the ballistics calculator on the Nikon website converts to inches in adjustment. Do I now apply the formula for inches to MOA? Once I have my MOA I can determine the amount of clicks needed based on the increment, i.e.(1/4, 1/8)? Is this correct? What I mean is, if I had an MOA of 1.5 and a scope that adjusts in 1/8th inch, could I just do 1.5 x 8 to get the number of clicks at any distance? Or do the increments get bigger with greater distance? Sorry for all the questions, I figure to you guys its probably easy. Thanks for all your help.
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M7025-06
Optics Apprentice Joined: January/21/2010 Location: Nebraska Status: Offline Points: 271 |
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If I'm way off, someone feel free to correct me.
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308 Sav
Optics Journeyman Joined: July/18/2010 Location: Kentucky Status: Offline Points: 362 |
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Yes most probably your scope adjusts in MOA at least 1/4 or 1/8 MOA. It could adjust in inches at 100 or Shooters MOA. We all had to learn some where. There is a ton of information out there on the web. First of all I suggest you learn what an MOA is and how it correlates to shooting at distances. Inches measure a lineal dimension and MOA is a measurement of an angle. The conversion you seek sounds more complicated than it is. Us telling you is not going to make you understand it. MOA = (Number of inches / (yards distance/ 100)) / 1.047 Read these. http://www.mil-dot.com/index.htm good section on MOA
Ballistics calculator Use this one. You will need to know the information on what types of clicks your scope has and the load you are shooting. plug in your information such as click values of your scope and your load. Edited by 308 Sav - February/13/2011 at 18:21 |
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Gerald Baker
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bman940
Optics Apprentice Joined: July/31/2010 Location: Texas Status: Offline Points: 94 |
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Stryker, Nikon's Spot On site will let you choose if you want your corrections in inches (default setting) , clicks or MOA. It'll do it all for you.
Very helpful program from Nikon and it's FREE. Go to Nikonhunting.com, click the upper right hand corner, Spot On logo and register,then you'll have access to the sight. Let me know if you have any questions. Bart Nikon Pro Staff
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stryker86442
Optics GrassHopper Joined: February/11/2011 Location: Arizona Status: Offline Points: 10 |
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bman, I went to the NIkon spot on site and I can't find anywhere how to convert from inches to MOA, or clicks for that matter. Where do I go to change the setting? Thanks |
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bman940
Optics Apprentice Joined: July/31/2010 Location: Texas Status: Offline Points: 94 |
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If you go to Generate ballistic reports, click on generate ballistic tables, you can get drop in inches or MOA.
If you go to change atmospheric conditions you can get wind correction in inches,moa or clicks. Let me know if you have any problems Stryker. Bart |
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stryker86442
Optics GrassHopper Joined: February/11/2011 Location: Arizona Status: Offline Points: 10 |
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Thanks bman, that's exactly what i needed.
I'm pretty new to long range shooting and the way i see it is, if you adjusted for the inches and not the MOA your shot would be significantly off target, am I correct? Reason I ask being this is the only topic that I'm still confused on.
If I'm zeroed at 100 yds and want to shoot a target at 400 yds, i would adjust for the MOA, not the inches of drop, in elevaton to move the point of impact up. Yes?
To my understanding, minute of angle is just inches converted into a type of angular measurement. (Correct me if Im wrong, please.)
I wasn't sure how to word this so hopefully you can understand what I mean. Thanks for all your help.
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supertool73
Optics God Superstool Joined: January/03/2008 Status: Offline Points: 11814 |
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MOA has nothing to do with inches. MOA is a unit of angular measurement that is correct.
People just started making it into inches because it seems easier to understand. If you really want to understand it then forget all about inches just start thinking in MOA. Or mils as a lot of scopes are going to MIL adjustments these days. |
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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.
"A Liberal is a person who will give away everything they don't own." |
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supertool73
Optics God Superstool Joined: January/03/2008 Status: Offline Points: 11814 |
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THis will confuse the crap out of you at first. But keep reading it over and over, it will help a lot.
http://www.mil-dot.com/Content%20Images/The_Derivation_of_the_Range_Estimation_Equations.pdf |
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Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.
"A Liberal is a person who will give away everything they don't own." |
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biggreen747
Optics Journeyman Joined: October/16/2009 Location: Colorado Status: Offline Points: 470 |
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Once you understand whats written in that paper a light will come on and it will seem easy.
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We measure it with a micrometer, mark it with a crayon, and cut it with a chainsaw.
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stryker86442
Optics GrassHopper Joined: February/11/2011 Location: Arizona Status: Offline Points: 10 |
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Thanks for the lead on the Mil and MOA document, that was the easiest break down I've seen yet.
I have one more question for you seasoned shooters, I have a zero of 100 yds and need to adjust my elevation to shoot at 500 yards. I have a riflescope that adjusts in 1/8 MOA. Now, from a 100 yd zero, would each click up be in increments of 1/8 MOA or 5/8 MOA?
This is really all that I'm still confused on now. I know that when I was zeroing in at 100 yds each click was 1/8 MOA. Now if I wanted to adjust for distance I'm not sure if I still use the 100 yard increment or the 500 yard increment.
Almost there!!!!!!!!!
P.S. Anybody know where to get a ballistics report for Silver Bear .308 140 gr Soft Points? ( I know they are not quality rounds, but they are affordable.)
Thank you to all you guys.
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