Talk:Point-blank range

"Incorrect" Definition

Saying that a term has "incorrectly come to mean" is merely an editorial comment. While prescriptivists might prefer that the term keep its more technical meaning, people are not objectively "incorrect" to use the term "point blank" in the more commonly understood way. A hearty debate between prescriptivists and descriptivists could certainly ensue, but there is no reason for this page to take a position on whether a given common usage of a term is correct or not. — Preceding unsigned comment added by 97.126.219.147 (talk) 07:47, 30 September 2011 (UTC)

Need for a Chart

It would be nice to have a chart of common MPBR as part of this article. As a user of Wikipedia the article lacks a connection with the real world. What's the MPBR of a few common carrtridges, at least?? —Preceding unsigned comment added by 24.20.180.239 (talk) 17:24, 6 October 2009 (UTC)

This question is based on a misunderstanding of how a battlesight zero works. One cannot construct such a table, because MPBR (not a commonly used term among modern shooters) depends not only on cartridge specs, but on the configuration of the individual rifle. Setting a battlesight zero is a design tradeoff between minimizing deviation, and maximizing effective range. Frankly, this whole article reads like it was written by someone who had never actually zeroed a rifle, but did read some books about it once.

deviation

"If the sights are lower than the allowable deviation..."

What is meant by high and low sights? If a scope on your varmint rifle is 2 inches above the barrel and parallel to the barrel then the bullet should hit two inches below your cross hairs at short distances. Is the sight 2 inches high in this case? If the sight was 1 inch above the barrel then your range would be greater? --Gbleem 14:50, 22 September 2006 (UTC)

To visualize this, assume we have a perfectly horizontal line of sight through the sights at the target, and assume the bullet follows a parabolic arc--the true path will be somewhat squished due to air resistance, but a parabola is close enough for this though experiment.

Now if we only care about sighting in for one exact range, then we can alter than flatness of the parabola as needed, by tilting the barrel, until the parabola crosses the light of sight at any desired point within the maximum range of the bullet. For short ranges, it would be easiest to cross the line of sight on the rise, for long ranges, on the fall.

Let's assume we have a case where, if the sights are eactly level with the muzzle, we cross the line of sight at 0 and 100 meters, and our midrange trajectory is 10 cm above the line of sight. If we're shooting, say, prarie dogs, that 10 cm midrange trajectory means that we're going to miss high when aiming at prarie dogs that are about 50 m distant, even though we can hit the close ones and the far ones. If we change the angle of the barrel, then we can drop our midrange trajectory, but we also cut down our maximum range, because the bullet is going to drop below the line of sight far sooner than it was with the high mid-range trajectory.

So what we need to do to ensure that we can hit the prarie dogs anywhere from 0 to 100 meters is to keep the curve to our trajectory, but move the line of sight so that our midrange trajectory is less high relative to the line of sight. By raising the line of sight by 5 cm, we are now going to hit 5 cm low at 0 m, 5 cm high at 50 m, and 5 cm low at 100 m. Now, if it is the case that a prarie dog sticks its head out of its hole about 10 cm worth, then aming at the middle of the prarie dog will get us a hit at any range from 0 to 100 meters.

Since generally shots aren't going to be taken at very close ranges, it's actually advantageous to set your sights higher than the target radius, so that you can push the midrange trajectory out as far as possible, because that's the limiting factor in maximizing the point blank range. However, most people find high sights unattractive and awkard to use, so low sights are probably here to stay. scot 15:31, 22 September 2006 (UTC)

Calculation

The section on calculating point blank range is completely wrong. It describes basic ballistic principals about for when a horizontally fired bullet will strike the ground but doesn't mention anything about the height of the line of sight above the barrel or the angle of the barrel relative to the line of sight. If you picture a graph of the bullets drop as a downwards parabola with a straight line for the line of sight then you can see the complexity of and simplicity of calculating the zero points. Depending on the angle of the LOS(line of sight) you can have the bullet cross it twice (for example at 50 and 200 meters for some .223 rifles), intersect it once or even always stay below it. These intersections are the zero points of the rifle that are typically adjusted to suit the user. To either side of the zero there are point blank ranges. Effilcdar (talk) 00:25, 24 October 2011 (UTC)

One example to picture is a rifle with the scope six inches above the barrel. If you fired it with the scope pointed at something an inch in front of the gun than the gun will obviously be shooting 6" low. Now it is obvious you will have to point the scope down (or the barrel up) to have them intersect at say 50m. If you adjust the scope to "zero" at 50m you will find that it is putting bullet holes low before 50m and high after it until the drop brings it back down to cross the sight plane at the second zero for example at 200m. If a high velocity bullet is used the trajectory is used relatively flat and stays within a few inches of zero well past the range of the second zero point. If it is a low velocity round zeroing at 200m might result in it being as much as a foot high at 100 so much care is taken to choose good zero points to achive a maximum point blank and effective range. Effilcdar (talk) 00:25, 24 October 2011 (UTC)

I agree it does not make sense. I moved it to below for future reference. Mikael Häggström (talk) 15:53, 3 February 2013 (UTC)

Calculating point-blank range A projectile falls due to gravity once it leaves a weapon barrel. All objects at the same geographic location fall with the same acceleration, denoted g, roughly 9.8 m/s² (32 ft/s²). Velocity is a vector; the vertical component of any projectile's velocity can be treated separately from the horizontal component. If the barrel is horizontal and at height h above the ground, then Newton's equations of motion can be used to show that the range is approximately $\scriptstyle v{\sqrt {\frac {2h}{g}}}$, where v is the muzzle velocity. This calculated range is reduced by air resistance. The air resistance depends on at least the frontal area of the projectile, the drag coefficient, air density and the speed of the projectile—making the problem a differential equation.

Definition

I've always know the definition of point-blank-range as per this link. It seems very straight forward defining the first and second point-blank-primitives and the distance between them. However I see none of this in the wiki article. I'm now questioning my long understood definition. — Preceding unsigned comment added by 64.201.178.186 (talk) 04:26, 24 February 2013 (UTC)

Hydro static Shock

I am removing refrences to hydrostatic shock in this article because it is

1. 1 out of scope of this article
2. 2 Very much debated

If you have issues with this I shall point please post on my talk page --Youngdrake (talk) 16:43, 24 June 2014 (UTC)

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shot point should not reditect here

It has a completely different meaning in geophysics. (See Semblance analysis Elinruby (talk)