Bonus Podcast: Gresham on Guns - That Old Devil, Gravity

Published on August 21, 2015
Duration: 12:47

This podcast episode, originally from 2001, revisits the fundamental physics of bullet trajectory. Tom Gresham explains that a bullet drops from the moment it leaves the muzzle due to gravity, and its apparent upward path is a result of the scope being mounted higher than the barrel, requiring the barrel to aim upward to intersect the line of sight. The discussion also covers how uphill and downhill shooting angles affect bullet impact and the importance of understanding trajectory for accurate shooting.

Quick Summary

A rifle bullet drops due to gravity the instant it leaves the muzzle. Its apparent upward path is due to the scope being mounted higher than the barrel, requiring the barrel to aim upward to intersect the line of sight. This causes the bullet to cross the sight line twice: once on the way up and again on the way down.

Chapters

  1. 00:00Introduction and Podcast Origin
  2. 00:39Personal Note: GunDeo App Featured in Forbes
  3. 01:35Article Title: That Old Devil Gravity
  4. 01:40Defining Exterior Ballistics
  5. 02:03Misconceptions About Bullet Path
  6. 02:25Illustrating Bullet Trajectory
  7. 03:08BB Gun Analogy for Trajectory
  8. 03:23Bullet Drop from Muzzle
  9. 03:52Why Bullets Hit High at 100-200 Yards
  10. 04:02Scope Height vs. Bore Alignment
  11. 04:17Bullet Crossing Line of Sight Twice
  12. 04:42Outfielder Analogy for Trajectory
  13. 04:58Using Trajectory Tables
  14. 05:06Impact of Elevation on Trajectory
  15. 05:27Shooting Uphill and Downhill
  16. 05:51Physics of Uphill/Downhill Shooting
  17. 06:16Mental Exercise: Straight Up/Down Shot
  18. 06:51Importance of Trajectory Charts
  19. 07:15Pistol Bullet Example
  20. 07:41Evolution of Long Range Shooting
  21. 08:22Political Commentary: Gun Rights and Voting
  22. 10:07Ongoing Battle for Gun Rights
  23. 11:09Opportunity to Get Involved
  24. 12:03Bringing New People into Shooting Sports
  25. 12:31Concluding Thoughts on Gravity

Frequently Asked Questions

What is exterior ballistics and how does it affect a bullet's path?

Exterior ballistics studies a projectile's flight from muzzle to target. A bullet drops due to gravity the moment it leaves the barrel. Its trajectory is a curve that begins nearly flat and becomes steeper with distance, influenced by factors like initial velocity and air resistance.

Why does a rifle bullet seem to go up before coming down?

A rifle bullet appears to go up because the scope is mounted higher than the barrel. To align the sights, the barrel must point slightly upward. This causes the bullet to cross the line of sight around 25 yards on its way up, and again later as it falls back down.

How do uphill and downhill shooting angles affect bullet impact?

When shooting uphill or downhill at steep angles, the bullet will hit higher than expected. This is because the horizontal distance the bullet travels is effectively reduced. To compensate, you must aim lower on the target.

Where can I find information on bullet trajectory for my rifle?

You can find detailed bullet trajectory information in loading manuals or catalogs from ammunition companies. It is also recommended to create a personalized drop chart for your specific rifle and tape it to your firearm for quick reference.

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