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Leveling the Scope Reticle for Long Range Rifles

 
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  #36  
Old 03-04-2013, 03:21 AM
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Re: Leveling the Scope Reticle for Long Range Rifles

Before you get too crazy about your ability or lack thereof to hold a rifle level...take a look at YouTube Long Range Blog 56 ...it is 5 mins viewing time. or copy paste & click
http://www.youtube.com/resultssearch....1.hgVYd_0yRSE

Your vestibular senses [seat-of-the-pants orientation in space] are better than one might think. In USAF Pilot Training we utilized the Barany acceleration/decelerattion Chair to trick the semi-circular canals of the inner ear...kind of UNcaging your gyro...pretty easy with eyes closed but, once you get a look at the horizon your body can get pretty darn good SA [situational awareness]...actually your tolerances are better than the manufacturing tolerances for some spirit levels !
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  #37  
Old 03-04-2013, 03:19 PM
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Re: Leveling the Scope Reticle for Long Range Rifles

I bought a Huskemaw scope last yr and took it in to Best of the West to install. They told me that they canted it about 2 to 2 1/2 degrees to account for spin drift. The segment on TV that someone was commenting on said they use 2 degrees if I remember it right. Bruce
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  #38  
Old 03-05-2013, 01:10 PM
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Re: Leveling the Scope Reticle for Long Range Rifles

Quote:
Originally Posted by CRaTxn View Post
Before you get too crazy about your ability or lack thereof to hold a rifle level...take a look at YouTube Long Range Blog 56 ...it is 5 mins viewing time. or copy paste & click
http://www.youtube.com/resultssearch....1.hgVYd_0yRSE

Your vestibular senses [seat-of-the-pants orientation in space] are better than one might think. In USAF Pilot Training we utilized the Barany acceleration/decelerattion Chair to trick the semi-circular canals of the inner ear...kind of UNcaging your gyro...pretty easy with eyes closed but, once you get a look at the horizon your body can get pretty darn good SA [situational awareness]...actually your tolerances are better than the manufacturing tolerances for some spirit levels !
I watched the video a few times. The vlogger attempted to show that in the presence of a visual spatial reference (mildot reticle against a natural scene), he could reproducibly return to the same inclination within 0.3 degree. His experiment was flawed, however, because the digital inclinometer was not oriented perpendicular to the rifle barrel. It was rotated about 45 degrees, apparently so that the camera could see the display and the vlogger’s face without putting the camera in front of the muzzle. His measurements of canting repeatability were probably lower than the actual repeatability.

The vlogger seemed to be mainly concerned about canting error changing his point of impact between shots. That’s a valid perspective if your primary concern is about group size. However, long range hunters are primarily concerned about cold bore, first shot accuracy.

Therefore, in the context of long range hunting, canting error is primarily an issue of angular accuracy. Reproducibility is an important factor too, but becomes moot if the accuracy is poor. The vlogger did not say anything about the accuracy of sensing true vertical, even though he had a digital inclinometer and could have done that experiment too.

Certainly, with an accurate spatial reference, like the horizon, surface of water, etc., a person can align a horizontal reticle line to true horizontal with reasonable accuracy. However, long range hunters don’t generally have such good spatial references.

Tests have proven that without the benefit of a true visual horizon line as a spatial reference, humans are not very good at determining true vertical. In a dark room, without any spatial reference, a healthy person in an upright sitting position can determine true vertical to within +/- 3 degrees. In this test the person is relying solely on vestibular senses and proprioceptive inputs (skin, muscles and joints) for balance. Put that person in a prone position on uneven terrain, tilt the head ~15 degrees in a cheek weld, and throw in a bunch of visual scene clutter, such as sloped terrain, trees, etc., and the accuracy of determining true vertical is going to be much worse.
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  #39  
Old 03-05-2013, 10:40 PM
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Re: Leveling the Scope Reticle for Long Range Rifles

I think we are making mountains out of mole hills! The key is understanding that those long range compensated shots are completly dependant on the scope being perfectly vertical. The angle of the gun can be canted left or right quite a bit with no effect as long as the scope is vertical. Everyone holds their gun differently and in my opinion , it is more important to hold the gun comfortably and set the scope vertical . Yes the next guy on the gun will say the scope is crooked but if it is equiped with a level, it will shoot the same group if he pays attention to the level. There is nothing worse than setting someone up for a shot at long range and they forget to look at the level. If the gun comes up comfortably, it will be very close to level . Yes, spin drift plays a critical factor and when we do the scope set up on a 100 yard target, the scope is canted left about 2 degrees. I shoot a 100 yard group on the line and then dial up to 1000 yards and then want the group to be between .75 and 1 inch left of the line. Anyone who shoots longrange varmets will understand . With no wind, gun is dead on. right hold and left hold are the same for the same wind. Before, with the scope perfectly vertical, 2 mph wind from the left required a 2 MOA hold, same wind from the right required no hold. Just a small thing that makes life easier. I still sight guns in the old way. I take out the bolt and line up on a 25 yard target by eye. Two shots at that target and then to the 300yard and two more shots and I'm dead on. The bend in the barrel doesn't matter much, it is nice if it bows up, giving you more elevation with your scope without shims, but once the bullet leaves the barrel it can only go straight. Most of these little things don't mean much unless you are shooting less than 1/2 MOA . It was a great article but over the head of most, but all valed points!
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  #40  
Old 03-05-2013, 11:52 PM
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Re: Leveling the Scope Reticle for Long Range Rifles

Hey Phil and Bruce, Just pokin my head up over a 'mole hill' in regards to a couple of question marks that popped up while reading this..

Quote:
Originally Posted by paphil View Post
when we do the scope set up on a 100 yard target, the scope is canted left about 2 degrees.
Are you saying the scope is rotated counterclockwise 2 degrees or the base is angled off center 2 degrees?

I shoot a 100 yard group on the line and then dial up to 1000 yards and then want the group to be between .75 and 1 inch left of the line.
After you dial up to 1000yds, are you still shooting the same POA on the same 100yd target as the first group you fired?
And for the kicker.. why aren't barrels just manufactured with a left hand twist to counter combined coriolis and spin drift effects?

I've learned a lot from this thread, thanks everyone for taking the time to help us understand what's actually happening when we launch one downrange!



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  #41  
Old 03-05-2013, 11:59 PM
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Re: Leveling the Scope Reticle for Long Range Rifles

Quote:
Originally Posted by bruce_ventura View Post
I watched the video a few times. The vlogger attempted to show that in the presence of a visual spatial reference (mildot reticle against a natural scene), he could reproducibly return to the same inclination within 0.3 degree. His experiment was flawed, however, because the digital inclinometer was not oriented perpendicular to the rifle barrel. It was rotated about 45 degrees, apparently so that the camera could see the display and the vloggerís face without putting the camera in front of the muzzle. His measurements of canting repeatability were probably lower than the actual repeatability.

The vlogger seemed to be mainly concerned about canting error changing his point of impact between shots. Thatís a valid perspective if your primary concern is about group size. However, long range hunters are primarily concerned about cold bore, first shot accuracy.

Therefore, in the context of long range hunting, canting error is primarily an issue of angular accuracy. Reproducibility is an important factor too, but becomes moot if the accuracy is poor. The vlogger did not say anything about the accuracy of sensing true vertical, even though he had a digital inclinometer and could have done that experiment too.

Certainly, with an accurate spatial reference, like the horizon, surface of water, etc., a person can align a horizontal reticle line to true horizontal with reasonable accuracy. However, long range hunters donít generally have such good spatial references.

Tests have proven that without the benefit of a true visual horizon line as a spatial reference, humans are not very good at determining true vertical. In a dark room, without any spatial reference, a healthy person in an upright sitting position can determine true vertical to within +/- 3 degrees. In this test the person is relying solely on vestibular senses and proprioceptive inputs (skin, muscles and joints) for balance. Put that person in a prone position on uneven terrain, tilt the head ~15 degrees in a cheek weld, and throw in a bunch of visual scene clutter, such as sloped terrain, trees, etc., and the accuracy of determining true vertical is going to be much worse.
Quote:
Originally Posted by bruce_ventura View Post
I watched the video a few times. The vlogger attempted[ AN ATTEMPT THAT HITS THE TARGET IS NOT AN ATTEMPT BUT A "PROOF">CR] to show that in the presence of a visual spatial reference[ IN MHO IF YOU DO NOT HAVE VISUAL REFERENCE YOU CAN NOT ETHICALLY SHOOT LRH BECAUSE THE TOF MEANS AN UNWANTED ANIMAL OR OTHER SAFETY FACTOR COULD MOVE INTO THE POI BY THE TIME OF BULLET STRIKE>CR] (mildot reticle against a natural scene), he could reproducibly return to the same inclination within 0.3 degree. His experiment was flawed, however, because the digital inclinometer was not oriented perpendicular to the rifle barrel[I DISAGREE HERE BECAUSE THE SENSOR WAS OVER THE BORE WHILE THE INDICATOR FACE WAS TURNED FOR SAFETY AS YOU MENTION--AWAY FROM THE MUZZLE>CR] . It was rotated about 45 degrees, apparently so that the camera could see the display and the vloggerís face without putting the camera in front of the muzzle. His measurements of canting repeatability were probably lower than the actual repeatability[OBVIOUS TO THE OBSERVERS EYES HIS REPEATABILITY WERE AS THEY WERE -AS WE ACTUALLY SEE-ON FLIM NO PARALYSIS-OF-ANALYSIS REQUIRED>CR].

The vlogger seemed to be mainly concerned about canting error changing his point of impact between shots. Thatís a valid perspective if your primary concern is about group size. However, long range hunters are primarily concerned about cold bore, first shot accuracy[HE HITS THE TARGET COLD BARREL(NORWEGIAN WOOD COLD) ON FILM...I GIVE THAT MORE CREDIBILITY THAN TYPE ON PAPER OR COMPUTER SCREEN>CR]

Therefore, in the context of long range hunting[IF YOU DON'T THINK THE TERRAIN IN THESE VIDEOS (MANY ON ACTUAL ROE DEER CULLING OPERATIONS) AREN'T REAL WORLD ENOUGH???I DON'T THINK RUGGED IRREGULAR MOUNTAINS & RIDGES FOR BACKDROP CAN BE ANY MORE PURE UNLESS AN ANIMAL DIES>CR], canting error is primarily an issue of angular accuracy. Reproducibility is an important factor too, but becomes moot if the accuracy is poor[WHERE IN THE YouTubes DO YOU SEE ANYTHING THAT COULD BE CONSTRUED AS "POOR">CR]. The vlogger did not say anything about the accuracy of sensing true vertical[THOMAS IS MULTI-LINGUAL BUT HIS BLOG IS VISITED BY MANY LANGUAGES THUS HE EMPLOYS A MIME'S GESTURAL BODY LANGUAGE TO CONVEY HIS INTENT..AND VERY WELL IF YOU READ THE RESPONSES BELOW HIS ART>CR], even though he had a digital inclinometer and could have done that experiment too.

Certainly, with an accurate spatial reference, like the horizon, surface of water, etc., a person can align a horizontal reticle line to true horizontal with reasonable accuracy. However, long range hunters donít generally have such good spatial references. [SEE MY REMARKS FOR LRH TOF AND SAFETY BELOW>CR]

Tests[WHAT TESTS ARE YOU REFERENCING..IN MY POST I SPEAK OF PERSONAL AND OBSERVED BARANY CHAIR CLASSES WITH THE USAF INSTRUCTOR PILOTS /CLASS ROOM INSTRUCTORS SUPERVISING>CR] have proven that without the benefit of a true visual horizon line as a spatial reference, humans are not very good at determining true vertical[ WHAT DID YOUR EYES TELL YOUR BRAIN ABOUT REPEATABILITY DURING AND AFTER YOU WATCHED BLOG #56/>CR][BRUCE MY DEBATE IS WITH THIS CONCEPT EXPRESSED AND REAL WORLD FILMED REALITY; I TRUST IT WILL GENERATE THOUGHT AND TESTING BY MANY WHO READ IT --SHOOTING YEA--YOU SHOULD BE VERY PROUD OF YOUR ART i.e. WRITING AS IT HAS ELICITED SEVERAL RESPONSES AND AFTER ALL ISN'T THAT THE POINT OF ALL THIS?]. In a dark room, without any spatial reference, a healthy person in an upright sitting position can determine true vertical to within +/- 3 degrees. In this test the person is relying solely on vestibular senses and proprioceptive inputs (skin, muscles and joints) for balance[I CONCUR 100%>CR]. Put that person in a prone position on uneven terrain, tilt the head ~15 degrees in a cheek weld, and throw in a bunch of visual scene clutter, such as sloped terrain, trees, etc., and the accuracy of determining true vertical is going to be much worse.
>>>>>>>>>><<<<<<<<<<
i certainly enjoyed reading the depth of theoretical analysis our scholar invested in the article. Likewise I have no wish to attack a LRH sponsor, especially one that can give the blind a lighted path to "some" illumination BUTT, though we may have all been created equal in the eyes of our lord... our lord did NOT create all our eyes nor vestibular senses equal. All I am saying is, IF you think you need this or any device...you probably do.
IF a serious LRH watched all 60 "V"logs of Thomas Haugland you will see Practical Precision Accuracy out to 1600meters NOT yards with production [though German and European ] rifles & optics. When one can and does on film hit specific rocks and subMOA steel targets repeatedly cold barrel first shot...that my boy is not shooting for group...it is field accuracy at its finest.Bruce if you think the tremendous accuracy displayed on the these YouTube Long Range Blog [start with#56] clips "vlogger's" trips to rugged windy intermountain hunting type terrain was merely "an attempt " then I request you do a short tutorial video of your "attempt" at displaying what you consider " proper angular accuracy".
You make some strange comments ..I THINK I CAN ADDRESS THEM BEST BY MAKING MY COMMENTS IN CAPS NEXT TO YOUR SPECIFIC REMARKS ABOVE...i.e. the rest of my post is imbedded above...IN CAP>CR
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  #42  
Old 03-06-2013, 01:23 AM
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Phil,

Thanks for jumping in. My experience with spin drift is limited. I take it you put a 2 degree cant on the scope for all long range rifles, regardless of the specific BC, bullet length and twist rate. Do you have a method of setting that cant angle in the shop, or do you dial it in at the range using the live fire method?
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