Sponsers of Long Range Shooter

05/25/08 0857 hours

Sportsman’s outfit
Sportsman’s Outfit is a store and community serving hunters and fishermen. We have access to over 2,000 products.

Lex Talus Corporation
Lex Talus Corporation has designed two interrelated ballistic software products: a desktop program called the “Precision Shooter’s Workbench©” and the “Field Firing Solutions©”, a real-time field version designed to generate firing solutions in the field from a PDA using current atmospheric and target data.

Berger Bullets
Today, Berger Bullets operates several custom built machines that monitor pressure and reject bullets that are outside of required tolerances. These machines are more consistent than a hand press operation by using presses that provide accurately repeatable travel and speed. When combined with the highest-grade materials available we create a bullet that achieves the ultimate in consistency from box to box within a lot. Compare the results of this process to the mass produced bullets and you will find the reason why their bullets need to be sorted by accuracy minded shooters while Bergers do not.

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Pictures

05/23/08 0904 hours

Ghillie Suit

down hill shooting

Deer 2007 hunt

2007 hunt with Jonas

Good view

A little R&R

Ghillie suit hide and seek with the kids

Sean

Heath from passthebrass.com

Sean

Chad from sportsmansoutfit.com

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Support our Troops

05/20/08 0844 hours

Check out this video in support of our troops
War Wounds

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Transonic Problem

05/16/08 0004 hours

When the velocity of a rifle bullet fired at supersonic muzzle velocity approaches the speed of sound it enters the transonic region. In the transonic region, an important thing that happens to most bullets, is that the centre of pressure (CP) shifts forward as the bullet decelerates. That CP shift affects the (dynamic) stability of the bullet. If the bullet is not well stabilized, it can not remain pointing forward through the transonic region (the bullets starts to exhibit an unwanted coneing motion that, if not dampened out, can eventually end in uncontrollable tumbling along the length axis). However, even if the bullet has sufficient stability (static and dynamic) to be able to fly through the transonic region and stays pointing forward, it is still affected. The erratic and sudden CP shift and (temporary) decrease of dynamic stability can cause significant dispersion (and hence significant accuracy decay), even if the bullet’s flight becomes well behaved again when it enters the subsonic region. This makes accurately predicting the ballistic behaviour of bullets in the transonic region very hard. Because of this marksmen normally restrict themselves to engaging targets within the supersonic range of the bullet used.

Posted by Sean in Effects on Ballistic* Comments (4)

Vertical angles

05/16/08 0000 hours

The vertical angle (or elevation) of a shot will also affect the trajectory of the shot. Ballistic tables for small calibre projectiles (fired from pistols or rifles) assume that gravity is acting nearly perpendicular to the bullet path. If the angle is up or down, then the perpendicular acceleration will actually be less. The effect of the path wise acceleration component will be negligible, so shooting up or downhill will both result in a similar decrease in bullet drop

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Ambient air density

05/16/08 0000 hours

Air temperature, pressure, altitude and humidity variations make up the ambient air density. Decreased air density will result in a decrease in drag, and increased air density will result in a rise in drag. Humidity has a counter intuitive impact. Since water vapor has a density of 0.8 grams per litre, while dry air averages about 1.225 grams per litre, higher humidity actually decreases the air density, and therefore decreases the drag.

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Wind

05/15/08 2359 hours

Wind has a range of effects, the first being the effect of making the bullet deviate to the side. From a scientific perspective, the “wind pushing on the side of the bullet” is not what causes wind drift. What causes wind drift is drag. Drag makes the bullet turn into the wind, keeping the centre of air pressure on its nose. This causes the nose to be cocked (from your perspective) into the wind, the base is cocked (from your perspective) “downwind.” So, (again from your perspective), the drag is pushing the bullet downwind making bullets follow the wind. A somewhat less obvious effect is caused by head or tailwinds. A headwind will slightly increase the relative velocity of the projectile, and increase drag and the corresponding drop. A tailwind will reduce the drag and the bullet drop. In the real world pure head or tailwinds are rare, since wind seldom is constant in force and direction and normally interacts with the terrain it is blowing over. This often makes ultra long range shooting in head or tailwind conditions hard.

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Coriolis effect

05/15/08 2354 hours

The coordinate system that is used to specify the location of the point of firing and the location of the target is the system of latitudes and longitudes, which is in fact a rotating coordinate system, since the Earth is rotating. For small arms, this rotation is generally insignificant, but for ballistic projectiles with long flight times, such as extreme long-range rifle projectiles, artillery and intercontinental ballistic missiles, it is a significant factor in calculating the trajectory. During its flight, the projectile moves in a straight line (not counting gravitation and air resistance for now). Since the target is co-rotating with the Earth, it is in fact a moving target, relative to the projectile, so in order to hit it the gun must be aimed to the point where the projectile and the target will arrive simultaneously.

When the straight path of the projectile is plotted in the rotating coordinate system that is used, then this path appears as curvilinear. The fact that the coordinate system is rotating must be taken into account, and this is achieved by adding terms for a “centrifugal force” and a “Coriolis effect” to the equations of motion. When the appropriate Coriolis term is added to the equation of motion the predicted path with respect to the rotating coordinate system is curvilinear, corresponding to the actual straight line motion of the projectile.

For an observer with his frame of reference in the northern hemisphere Coriolis makes the projectile appear to curve over to the right. Actually it is not the projectile swinging to the right but the earth (frame of reference) swinging to the left which produces this result. The opposite will seem to happen in the southern hemisphere. The Coriolis effect is latitude dependent and is at its maximum at the poles and negligible at the equator of the Earth. The reason for this is that the Coriolis effect depends on the vector of the angular velocity of the earth´s rotation with respect to xyz - coordinate system (frame of reference).

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Spin drift

05/15/08 2354 hours

Even in complete calm air, with no sideways air movement at all, a bullet will experience a spin induced sideways component. For a right hand (clockwise) direction of rotation this component will always be to the right. This is because the bullet’s longitudinal axis and the direction of the velocity of the center of gravity (CG) deviate by a small angle, which is said to be the equilibrium yaw or the yaw of repose. For right-handed (clockwise) spin bullets, the bullet’s axis of symmetry generally points to the right and a little bit upward with respect to the direction of the velocity vector. As an effect of this small inclination, there is a continuous air stream, which tends to deflect the bullet to the right. Thus the occurrence of the yaw of repose is the reason for bullet drift to the right (for right-handed spin) or to the left (for left-handed spin). This means that the bullet is “skidding” sideways at any given moment, and thus experiencing a sideways component.

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Field Firing Solutions

05/15/08 2103 hours

When I first started to shoot long distance, I started with Sierra I-5 ballistic software. I first thought that it would be the answer to my prayers. It had everything I needed and it would account for all the atmospheric conditions that I would encounter while shooting. But when I pulled the trigger guess what, a miss. I thought that because I could not make in field changes, that it was causing the bullet to miss the target. The real problem laid in the way the software accounts for bullet drop. A long time ago a man called Mayevski came up with a standard projectile flight path around the turn of the 20th century that all other bullets would be based off of. The problem is that the standard bullet weighed about one pound and was about one inch in diameter with a very blunt nose. Witch could not be compare to today’s modern bullets. So basing your flight path from this out of date technology became very difficult to do. You had to break down your flight path into different velocity regions and assign a different BC (ballistic coefficiency) in each region. The Lex Talus Corporation has come out with Field Firing Solutions. Software that, instead of using Mayevski drag function, uses a deceleration constant. This allows you to use only one BC value on your flight path. If that wasn’t enough, it gives you the ability to use angle cosine and coriolis drift to calculate your shot. The software was made to give you cold bore shots, and does it well. Plus with the ability to put the software on a PDA, it gives you great control over the atmospheric conditions that you will encounter in the field. In my days of shooting I have seen several types of ballistic software and not one can give me the type of control that this one delivers. It’s very easy to use and understand. In my opinion, to purchase this software would be one of the best choices you could make for shooting long distance.

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