Ruprecht Nennstiel, a forensic ballistics expert from Wiesbaden, Germany, has authored a great resource about bullet behavior in flight. Nennstiel’s comprehensive article, How Do Bullets Fly, explains all the forces which affect bullet flight including gravity, wind, gyroscopic effects, aerodynamic drag, and lift. Nennstiel even explains the rather arcane Magnus Force and Coriolis Effect which come into play at long ranges. Nennstiel’s remarkable resource contains many useful illustrations plus new experimental observations of bullets fired from small arms, both at short and at long ranges.

Shadowgraph of .308 Winchester Bullet

A convenient index is provided so you can study each particular force in sequence. Writing with clear, precise prose, Nennstiel explains each key factor that affects external ballistics. For starters, we all know that bullets spin when launched from a rifled barrel. But Nennstiel explains in greater detail how this spinning creates gyroscopic stability:

“The overturning moment MW tends to rotate the bullet about an axis, which goes through the CG (center of gravity) and which is perpendicular to the plane of drag, the plane, formed by the velocity vector ‘v’ and the longitudinal axis of the bullet. In the absence of spin, the yaw angle ‘δ’ would grow and the bullet would tumble.

If the bullet has sufficient spin, saying if it rotates fast enough about its axis of form, the gyroscopic effect takes place: the bullet’s longitudinal axis moves into the direction of the overturning moment, perpendicular to the plane of drag. This axis shift however alters the plane of drag, which then rotates about the velocity vector. This movement is called precession or slow mode oscillation.”

Raise Your Ballistic IQ
Though comprehensible to the average reader with some grounding in basic physics, Nennstiel’s work is really the equivalent of a Ph.D thesis in external ballistics. You could easily spend hours reading (and re-reading) all the primary material as well as the detailed FAQ section. But we think it’s worth plowing into How Do Bullets Fly from start to finish. We suggest you bookmark the page for future reference. You can also download the complete article for future reference and offline reading.

CLICK HERE to download “How Do Bullets Fly” complete text. (1.2 MB .zip file)

Photo and diagram © 2005-2009 Ruprecht Nennstiel, All Rights Reserved.

This amazing video features a variety of firearms: suppressed 9mm pistol, .338 Norma rifle, .300 WinMag rifle, 12ga comp’d shotgun, plus an AR15 and AR10.

This Must-Watch Video Has Some Amazing Ultra-Slow-Motion Segments

Watch the ultra-slow motion segment at the 2:55 mark and you can actually see a .30-cal bullet spin its way through the muzzle brake, leaving trail of flame that blows out the ports. Interestingly, at the 3:10 mark, you can also see a bright “afterburn” ball of fire that forms a few inches ahead of the muzzle milliseconds after the bullet has left the barrel. Perhaps this is late ignition of unburned powder?

Proof Research (PR) sells high-grade hunting and tactical rifles built with PR-made actions and carbon-wrapped barrels. For more information, visit ProofResearch.com.

Credit Steve of TheFirearmBlog.com for this YouTube video. Footage by JNZ for Proof Research.

In addition, BulletFlight 4.0.0 comes with a large database of bullet types (including weights, BCs etc.). You can also create your own custom ammo profiles (with velocity, BC, bullet type), allowing you to easily output ballistic plots for multiple firearms, without having to enter the rifle/bullet profile every time. The latest 4.0.0 version is faster than before, and 299 more projectile types have been added to the bullet database.

BulletFlight 4.0.0 is a very sophisticated program that rivals anything you can run on your home computer. A version of BulletFlight is already in use with the U.S. Military in Iraq and Afghanistan. The Apple operating system and “multi-touch” screen allows an extremely user-friendly interface. (And with the I-Pod Touch, you do NOT need a phone service contract.) “Ruggedized” Otterbox carry cases are also available for both first- and second-generation I-pods.

Software Starts at Just $3.99
There are three versions of KAC BulletFlight, all very affordable. The basic BulletFlt L1 edition (3.1.0 version) costs just $3.99. We recommend the BulltFlt L2 edition (3.1.0 version). At $11.99, the L2 software adds a full calculation screen, the ability to generate a range-card, cosine-angle calculation, and GPS functionality. Finally, the $29.99 BulletFlight Level ‘M’ 4.0.0 version further adds the ability to calculate an actual BC based on bullet drop, two velocities, or flight time. The Level ‘M’ version can also correct for subtle factors, such as the Coriolis Effects, which come into play at ultra-long ranges.