Whether you handload (and, you really should) or you shoot factory ammunition, the Laws of Physics have total control over the bullet - from the moment the firing pin strikes the primer until the bullet hits the target or its speed drops to zero and Gravity wins.

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Shoot an arrow, fire a cannon or throw a rock 25 feet, as the distance from the starting point to the intended ending point increases, so, too, must the trajectory of the object increase on its journey.

 

An aircraft in flight relies on engine thrust SPEED, wings LIFT (airfoil - high pressure created at the bottom of the airfoil and low pressure created at the top), elevator LIFT (a proportionally sized airfoil at the back) and a rudder LATERAL CONTROL (a vertical airfoil that controls yaw).  Obeying the Laws of Physics, high pressure flows into low pressure. This is the explanation why the largest and heaviest aircrafts takeoff, climb and maintain altitude apparently effortlessly. High pressure is generated below the wing or airfoil and low pressure is created on the top of the wing.  The airplane is essentially sucked UP into the air as lower and lower pressure is built on the top of the wing. Onboard computers, servo motors, aircraft operational specifications and wires and cables combine to control every aspect of a safe flight.  Enter Fly-by-Wire.

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Getting back on topic... every bullet has a weight (in grains), a ballistic coefficient (B/C - a number specifying its ability to fly through the air), a length (in inches) - from the base of the bullet to the bullet tip or meplat. The bullet's base may be a flat base design or a boattail design - an aerodynamic consideration. Bullets may be of a solid material or a mix of materials.  And, typically, as it applies to rifle ammunition, bullets are wrapped in copper. We've heard of FMJ or full metal jacket.

 

WHERE DO WE GO FROM HERE?

Well.  As the bullet leaves the muzzle, GRAVITY immediately kicks in. The bullet begins to DROP under gravity's influence. How long will it fly before it hits the ground? That depends of the SPEED of the bullet in FPS (feet per second). The math used to figure this out can be daunting. So, we rely on ballistic calculators to give us answers - more like suggestions, though.  Staying on track... the path or trajectory in its flight - when viewed laterally - is clearly NOT in a straight line.  The path until it hits the ground forms an arc - a segment of a circle.

 

In the Riflescopes menu, we mentioned height over bore. The height the riflescope sits above the barrel. The riflescope provides a line of sight - a straight line. This line of sight is unaffected by gravity and remains true to infinity. The barrel is (assumed) straight as well. One could conjecture that without gravity's immediate influence on the bullet when it leaves the muzzle, the bullet's path and the riflescope's line of sight would remain parallel. Not happening!

 

What does zeroing the rifle accomplish? Zeroing the rifle (barrel) to the scope's TRUE line of sight involves picking a known, fixed target distance... perhaps 100yds or 200yds? Your choice. That height over bore value usually translates to adjusting the elevation turret UP or DOWN such that the reticle's crosshair (POA) and the barrel's (bullet's) point of impact (POI) are identical.  We've subtly canted our rifle's muzzle UP similar to canting our arrow's tip UP or canting the cannon's muzzle UP. The bullet now travels in an upward ARC from the moment it leaves the muzzle.

 

Depending on the powder charge (load) and the power that load generates (FPS), if we visualize the TRUE line of sight of the riflescope, the bullet leaves the muzzle BELOW the line of sight (height over bore), passes through the line of sight, continues the upward trajectory while loosing speed until gravity takes over and the bullet begins to drop.  It passes through the line of sight a second time at some distance further out and hits the ground even further out. So, the bullet intersects the line of sight twice!

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Our only concern is, at what distance from the muzzle did the bullet first pass through the line of sight the first time and at what distance did it pass through the line of sight the second time. The distance between intercept #1 and intercept #2 represents a distance RANGE.

 

What was the bullet's APEX or height along the arc - above the line of sight - at the moment it began to drop. That value represents the radius of a circle. Multiply the radius by 2 and we have the diameter of a circle.

 

Let's visualize a length of PVC pipe and calculate its length and diameter.​ If the APEX is 5", the diameter of the PVC pipe is 10".  Cut the pipe to a length of intercept #1 to intercept #2.  This visualization represents MPBR.

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HOW DOES MPBR HELP ME?

​The two (2) images at the top of this page were made using an inexpensive Mobile Phone APP named Strelok Pro. - a Ballistics Calculator.  The image on the LEFT representative what one sees when 'on target'. The image on the RIGHT is a shooting solution; a computation of MPBR based on the rifle, riflescope, ammunition, temperature, pressure and humidity entered into the Ballistics Calculator.

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If you're hunting, the vital POI is between 6" to 8".  Taking the MPBR computed from a 100yd or 200yd zero, simply pointing the crosshair at the vital area - ONCE THE POA IS WITHIN MPBR - you should be comfortably assured a good hit on the POA by just holding your zero.

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DO NOT TRY THIS AT HOME OR AT THE RANGE!  THIS IS PURELY A VISUALIZATION!  DON'T DO IT!

Using 10" as the diameter just calculated from the MPBR exercise. Cut the PVC pipe to the length. The validation of the work done is to set the rifle on a level surface. Set the PVC pipe on a level surface - at a distance from the muzzle where the bullet first intersected the line of sight.  Safety measures in place?  The rifle could be fired. The bullet will enter the pipe and travel the entire length of the pipe, never piercing the pipe, and exiting the pipe at the end, traveling some distance further until it hits the ground.

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Honestly.  I don't know of anyone who has actually done this project.  This discussion is intended to develop an understanding of ballistics, the range time needed to prove all aspects of the rifle, riflescope and bullet's performance and safely.  Building DOPE for this combination.

 

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Key take away in wrapping this up is...

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• #1 - Long range shooting is an expensive pursuit

• #2 - You're gonna have to put in the work

• #3 - It's easy to loose interest

• #4 - If self-critique or external critique is your achilles' heel? Find another pursuit

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DISCLAIMER!

The pictures above show a typical shooting solution calculated by a ballistics calculator. There are a number of online ballistics calculators... some developed by reputable bullet manufacturers. There are many variables - temperature, humidity, pressure, elevation, wind that influence what happens when the trigger is 'squeezed'.  We never pull the trigger! Your safety remains your responsibility! The more you practice a skill, mastery of that skill follows. Put in the work at the range so you become more proficient at competition or on a hunt. Please observe the RED highlighted information above.

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We accept no responsibility and/or liability for any adverse results incurred by you for (your) failing to understand you are responsible for your choices and decisions.  Guns, in general, are dangerous! Your failure to use any gun and ammunition in a safe manner remains your responsibility along with any consequences of your abuse!