Ammunition Science: Shotshell Ballistics

Here's how the science affects the way your shot flies.

by
posted on March 29, 2023
rst.jpg
The projectiles in most shotshell loads take the form of round pellets. From the earliest years, these pellets were made exclusively of lead, but some jurisdictions require non-lead pellets...which in turn spurred the development of pellets made from steel, bismuth and tungsten.

In flight, shotgun pellets conform to the same ballistic laws as other projectiles. Their trajectory is curved so they lose velocity and energy as they fly, and they are deflected by crosswinds. Most shooters do not think of shotgun pellets in this way, as the average range at which shotguns are used is very close. Therefore, these factors aren't significant for the average shotgun shooter. 

The sectional density of round shot projectiles is very poor due to their light weight. Round projectiles also have a poor ballistic coefficient, so they lose striking velocity and energy very quickly. This limits the effective range of shotshell pellets to 50 yards or so. Beyond that distance, individual pellets may not have sufficient striking energy to penetrate into the vital organs of live game. Also, the target may not receive a sufficient number of pellet hits due to low pattern density at long ranges.

Steel shot is much less dense than lead. Thus, steel shot pellets of a particular size weigh less than lead pellets of the same size. When fired at the same muzzle velocity, steel pellets have a lower ballistic coefficient, resulting in lower striking velocity and less striking energy than a lead pellet of the same diameter. To offset these limitations, ammunition makers recommend that shotgunners select steel shot two sizes larger than the lead shot they would normally use. (For example, to replace No. 6 lead shot with No. 4 steel shot.) Other lead substitutes, such as bismuth and tungsten-based alloys, are often sufficiently similar in density to lead that no such change in shot size is required.

Note that striking energy and the number of hits from each individual pellet on the target are the key factors in breaking clay targets or killing game ethically and cleanly. Serious shotgunners will carefully pattern their guns and loads to establish both the maximum range at which the minimum number of hits may be obtained, as well as to select the load that provides the most uniform pattern density at the desired range or ranges.

Latest

Legacy Shockey Lede
Legacy Shockey Lede

NRA Family Entertainment: "Legacy," Featuring Jim Shockey & Christensen Arms

Attendees will have a once-in-a-lifetime opportunity to experience a world premiere film in an intimate setting with hunt legend Jim Shockey.

The NRA Foundation Supports USA Shooting's Olympic Goals

The NRA Foundation’s support will help USA Shooting athletes represent the United States at the highest levels of competition in international shooting events.

Throwback Thursday: The Men & Guns of the Vietnam War

The most prominent firearm of the conflict in Vietnam is probably the M16 ... but its rise was anything but smooth.

Henry Repeating Arms' Guns for Great Causes: 50 Custom Rifles for Team Baylee

“There are few things in this world more unfair than a childhood cancer diagnosis,” said Anthony Imperato, Founder and CEO of Henry Repeating Arms.

5 Things to Ask Your Dove-Hunting Guide

Dove season is coming sooner than you know! Here's what to figure out ahead of time.

Coyote Pretty: Springfield Armory's New 1911 DS Prodigy Pistol Colorway

Springfield has just released this popular pistol in a Cerakote Coyote Brown finish ... and the last thing you could call it is "coyote ugly."

Interests



Get the best of NRA Family delivered to your inbox.