DEBUNKED – THREE SHOOTING MYTHS YOU LEARNED ON THE INTERNET

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What you take as shooting fact – may be fiction. Click and read to find out if you’ve been duped by these long-standing false truths. Then, go tell your friends and look smart.
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The effect of wind on your bullet down range has more impact than the wind at your muzzle. Right?

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Incorrect. Ok, before you start throwing your tomatoes, we’ll admit, the effect of wind on bullets is one of the hottest and most debated shooting topics – even by true experts. We’ll also admit this myth may not be entirely debunked. Now, I’m going to ask you to think of it like this. With most things attempted in life, it’s best to get off to a good start. This goes for your bullet too. The wind at your muzzle will be the first to affect your bullet – and will essentially point your bullet right or left. By doing this, your bullet is now essentially on an un intended vector. Barring being blocked by an obstruction – and therefore giving you a false reading – the wind at your location is the most critical. Will the wind it encounters through it’s time of flight effect it? Certainly – but not as much as what’s happening at your shooting position.


 

 The lower your scope-over-bore height, the better for accurate long-range shooting. Right?

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Incorrect. Take this example: Nobody complains about their custom rifle in an XLR chassis costing $5,000 (plus) dollars with a scope-over-bore height of 2.5 in. Why? Because it’s a hell-of-an-accurate and extremely effective long-range set up. In fact, no matter what a person spends, scope-over-bore height has little impact on accuracy/down-range performance at longer distances.

Now, depending on the rifle, it may have a dramatic effect on cheek weld, comfort and optimal sight picture, (which could impact shooter performance) but that is completely unrelated. Also of worthy note, scope-over-bore height should be accounted for in short-range scenarios (under 50 yards), due to the more dramatic angular relationship between the bore and the optic.

When we compared two identical 6.5 Creedmoor setups using a ballistic calculator (the only difference being scope-over-bore heights of 1.7 in versus 2.7 in.), here’s what we came up with.  At 1000 yards (a distance where any deficiencies should be greatly exaggerated), the rifle with the higher scope-over-bore height required 9.13 mils of adjustment to deliver its payload on target. Interestingly .25 mils less than the rifle with the lower scope-over-bore height. One could argue the rifle with the scope mounted higher performed slightly better. Bam! Myth busted.


I need a large diameter scope tube to let in more light for better light transmission at dawn and dusk. Right?

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Incorrect. Although it seems intuitive, a larger tube diameter has virtually nothing to do with light transmission. Sorry. However, it does serve a very distinct and important purpose. All things being equal, the amount of total travel a scope has is bigly determined by the scope’s tube diameter. In order for a riflescope’s windage and elevation to adjust, the internal erector assembly needs room to move within the main tube. More room to move equates to more travel. More travel allows you to dial more adjustment for longer shots.

14 thoughts on “DEBUNKED – THREE SHOOTING MYTHS YOU LEARNED ON THE INTERNET

    Scott Rogerson said:
    June 8, 2017 at 10:21 am

    Good stuff. Thanks.

    I also thought that ‘bigly’ was not a real word, but consider that myth busted as well.

    Like

    Adam Robertson said:
    June 8, 2017 at 10:58 am

    In regards to the wind debate, is like to point out that within shorter distances 100-200m wind deviations are negligible at best, unless you’re shooting through a tornado. At further distances as the bullet slows down its more subseptible to drift. I’m not saying that the wind at the firing point is unimportant, but I’d argue that what happens further down range is more important.

    Liked by 1 person

      vortexoptics responded:
      June 8, 2017 at 12:30 pm

      Great points! If your bullet begins its flight trajectory off-axis, though, then wind drift down range is going to be adding insult to injury if not taken into account. Both are important, but wind at the muzzle should certainly not be overlooked.

      Like

    Fact not Opinion said:
    June 8, 2017 at 11:10 am

    Terrible, misleading opinion-sold-as-fact article.
    Wind: “…this myth may not be entirely debunked.” = enough said. Even the experts can’t agree.
    Scope Height Over Bore: Even though I agree and testing has proven this, the test presented is seriously flawed. Used two different rifles- Where’s the constant variable that is required for any accurate experiment (the target does not suffice).
    Tube Diameter: Proven time and again in refraction tests, all things being equal, larger tube transmit more light. -In a dark room, drill a 1″ hole through the 12″ brick wall to the outside. Then, drill a 30mm hole. Do they both allow the same amount of light through the tube?

    Like

      longrangeshootingblog said:
      June 8, 2017 at 11:23 am

      You may be correct but the margin of which is so little it may not matter, what really dictates light transmission is the objective lense size.

      As for the scope over bore height they used a ballistic calculator for the test .. not actual firearms.

      Like

        vortexoptics responded:
        June 8, 2017 at 12:28 pm

        Objective lenses are one component of an entire optical system which can contain up to 15 different lenses, if not more in certain cases. They do have an effect on light transmission, but you can make the biggest objective in the world, and if the optical system behind it isn’t optimized for that size in design, then a scope with a smaller objective bell that is designed and optimized better will have better light transmission and all around better optical quality.

        Scope over bore height has very little effect when shooting long range. If you consider shooting at 1000 yards, like we used in the test, the difference in the angle that the barrel makes with the target and the center of the optical system is so small with a change of just an inch or so, it is essentially non-existent. The time where scope over bore height does begin to make a difference is only when you get to extreme close distances.

        Let us know if you have any questions!

        Like

      vortexoptics responded:
      June 8, 2017 at 12:24 pm

      Wind – The point here was to note the fact that wind down range is not necessarily the most important factor in shooting long range. In fact, wind at the muzzle should be considered as important, if not more, than wind down range.

      Scope Height Over Bore – The only time scope height over bore really has a significant factor on shooting is at extreme close ranges when there is a steep angle between the target, your barrel, and the optic. At that point, you do need a significant amount of adjustment to make up for the offset. As you extend out to longer ranges (It doesn’t take a whole lot), you flatten out those angles and at that point, regardless of how high your scope is (Within reason) it’s not going to have a significant impact at all on how much adjustment is needed to compensate for the offset. The important consideration for shooters should be clearing their barrel with the objective bell and putting the scope at a comfortable height for cheek weld.

      Tube Diameter – A very key element of riflescope mechanics is completely missed in your argument. The external scope tube has ***Absolutely nothing to do*** with light transmission at all. Inside of that external scope tube is an erector system which houses the optical train for the riflescope. This is where the lenses lie, and everything inside the inner erector system, along with the other lenses in the scope, have ***Everything*** to do with light transmission, optical quality, and anything else to do with the image you see through the scope. Simply increasing the diameter of the external scope tube will do absolutely nothing for your light transmission if all else inside is kept the same. Light transmission, and other optical qualities, are determined entirely by optical design – spacing of the lenses, curvature of the lenses, chemical compounds of glass used, and coatings used on the lenses to name a few.

      Please let us know if you have any questions.

      Like

    Jason said:
    July 20, 2017 at 10:01 am

    Isn’t part of scope over bore height conversation pertain to horizontal dispersion when the rifle/scope are canted. In other words the higher the height the more horizontal dispersion For equal degrees of cant?

    Like

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