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Bubble level for rifle
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<blockquote data-quote="Dave King" data-source="post: 40994" data-attributes="member: 3"><p>CAM</p><p></p><p> I know you were kidding on the 180 thing but we've actually shot in that manner, just wanted you to know folks are trying all kinds of stuff.</p><p></p><p> Sighted at 600..reduce error by 50% at 1200 but increase error at 100... ??? I'm not sure exactly what you're asking but I'll give it a whirl.</p><p></p><p> I'll assume you're asking about cant error. ****, I'm getting a little leery of talking about cant and stating values (my *** is beginning to look like that of a Mandrill).</p><p></p><p> Cant error is increased by the amount of offset/trajectory correction in the sighting system. This means that if you're sighted (zeroed) at a greater distance the deflection error is greater than if you were sighted (zeroed) for a somewhat shorter distance. The size of the base (the distant end) of the "cone" that projects from the center of the rifle bore to the line of sight "zero" distance determines the magnitude of the deflection cant could cause. For example, a 100 yard zero on an imaginary rifle would allow for about 3 MOA of correction (TOF "drop" for 100 yards ~ 2MOA and sighting system height ~1 MOA). This would make a "cone" with a base of 6 MOA. If you rotated the rifle in 1 degree increments and fired a round onto the same target using the same POA at each interval when you had completed a 360 degree rotation you'd have a circle 6 MOA in diameter. At 12 o'clock on that circle would be the round fired in the Zero -0- degree cant position, at six (6) o'clock would be the round fired at 180 degrees of cant (it'd be 6 MOA low).</p><p></p><p> Not let's figure the same for a zero of 600 yards. I'll guess you use a magnum and that your 600 yard zero is about 11 MOA (sea level) ON TOP of your 100 yard zero (a hidden ~3 MOA). You can see that if you perform the 100 yard "round robin" test again your "cone base" circle is going to be at least ~22 MOA plus the "hidden" 100 yard zero correction of ~3 MOA (but 6 MOA of "cone base"). Overall I'd say you would have a circle of about 28 MOA.</p><p></p><p> Of course if you had used a 1200 yard "zero" data set the cone base would be much larger but that's not the other part of the question. The other part of the question if whether or not the 1200 yard cant error would be decreased by 1/2 by using a 600 yard zero.</p><p></p><p> Then you say <strong><em>"nightforce NP2 sighted at 600 and not dialing dope? would this roughly reduce error by half at 1200?"</em></strong> I take it to mean that you would use hold overs to get to 1200 yards. By doing so you effectively raise the muzzle of the rifle as you use a lower aiming point in then scope, this is no different in my eyes that if you were to "dial on" the additional data, the "cone base" gets larger. So I guess the answer to the 600 yards zero, 1200 yard shot only 1/2 the error would be...no.</p><p></p><p></p><p>Anyone have thought on this?? Does this sound correct?</p><p></p><p></p><p><em>My out: I'm not a rocket scientist, ballistic expert, or college graduate. All this data is pure speculation on my part, it's based on things I've read, pondered on and "worked out" on my own. I could be wrong and if I am I'd like to know the correct method(s) and answer(s), so speak up, I'd appreciate it.</em></p></blockquote><p></p>
[QUOTE="Dave King, post: 40994, member: 3"] CAM I know you were kidding on the 180 thing but we've actually shot in that manner, just wanted you to know folks are trying all kinds of stuff. Sighted at 600..reduce error by 50% at 1200 but increase error at 100... ??? I'm not sure exactly what you're asking but I'll give it a whirl. I'll assume you're asking about cant error. ****, I'm getting a little leery of talking about cant and stating values (my *** is beginning to look like that of a Mandrill). Cant error is increased by the amount of offset/trajectory correction in the sighting system. This means that if you're sighted (zeroed) at a greater distance the deflection error is greater than if you were sighted (zeroed) for a somewhat shorter distance. The size of the base (the distant end) of the "cone" that projects from the center of the rifle bore to the line of sight "zero" distance determines the magnitude of the deflection cant could cause. For example, a 100 yard zero on an imaginary rifle would allow for about 3 MOA of correction (TOF "drop" for 100 yards ~ 2MOA and sighting system height ~1 MOA). This would make a "cone" with a base of 6 MOA. If you rotated the rifle in 1 degree increments and fired a round onto the same target using the same POA at each interval when you had completed a 360 degree rotation you'd have a circle 6 MOA in diameter. At 12 o'clock on that circle would be the round fired in the Zero -0- degree cant position, at six (6) o'clock would be the round fired at 180 degrees of cant (it'd be 6 MOA low). Not let's figure the same for a zero of 600 yards. I'll guess you use a magnum and that your 600 yard zero is about 11 MOA (sea level) ON TOP of your 100 yard zero (a hidden ~3 MOA). You can see that if you perform the 100 yard "round robin" test again your "cone base" circle is going to be at least ~22 MOA plus the "hidden" 100 yard zero correction of ~3 MOA (but 6 MOA of "cone base"). Overall I'd say you would have a circle of about 28 MOA. Of course if you had used a 1200 yard "zero" data set the cone base would be much larger but that's not the other part of the question. The other part of the question if whether or not the 1200 yard cant error would be decreased by 1/2 by using a 600 yard zero. Then you say [B][I]"nightforce NP2 sighted at 600 and not dialing dope? would this roughly reduce error by half at 1200?"[/I][/B][I][/I] I take it to mean that you would use hold overs to get to 1200 yards. By doing so you effectively raise the muzzle of the rifle as you use a lower aiming point in then scope, this is no different in my eyes that if you were to "dial on" the additional data, the "cone base" gets larger. So I guess the answer to the 600 yards zero, 1200 yard shot only 1/2 the error would be...no. Anyone have thought on this?? Does this sound correct? [I]My out: I'm not a rocket scientist, ballistic expert, or college graduate. All this data is pure speculation on my part, it's based on things I've read, pondered on and "worked out" on my own. I could be wrong and if I am I'd like to know the correct method(s) and answer(s), so speak up, I'd appreciate it.[/I] [/QUOTE]
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