Skip to main content

O'Connor's Practical Field Ballistics

O'Connor's Practical Field Ballistics

I've always considered myself a practical person, and I've felt that trait extends to my shooting and reloading. I've encountered too many shooters who get so tangled in the minutia that they end up with information overload.

Jack O'Connor had a huge influence on how we shoot and hunt today. Image courtesy of Bradford O'Connor. All rights reserved. Used with permission.

I've always considered myself a practical person, and I've felt that trait extends to my shooting and reloading. I've encountered too many shooters who get so tangled in the minutia that they end up with information overload.

There were landmark moments leading to this practicality. Realizing that a bullet's path is not an arc (a segment of a circle with a constant center), but rather a segment of a parabola, a curved line whose "apparent" center changes, was a big first step. The second was understanding that this parabolic path gets steeper the farther the bullet travels; the path is always flatter between the muzzle and the sight-in distance than it can ever be beyond that point.


Only recently did I fully understand how these ideas formed, as they are by no means my creative works. The seed was planted by the words of Jack O'Connor that I probably read in my preteen years. Jack O'Connor (1902-1978) probably wrote more on shooting and hunting than any other outdoor writer, and he had a huge influence on how we shoot and hunt today.


It was when I found some of my ancient O'Connor hardbacks while looking for another book that I began reacquainting myself with this very wise and practical man. In words I'd first read 50 years ago, I rediscovered a practicality that surely shaped the way I think about shooting.

As I reread these books, there were several points that I realized I had embraced. The first was basically, "Don't sight 'short' if your rife can do more." O'Connor talked about a .270 Winchester shooter he encountered who only sighted for 100 yards because he did not expect to get a longer shot than that. This goes back to the principle that the path between muzzle and sight-in point is flatter than the path beyond the sight-in point. With a longer sight-in, the guy could have been "on" at much greater distances without correcting elevation.


Another concept O'Connor embraced was that every animal has an area--not a point--where a bullet has a high chance of stopping it. The bigger the animal, the bigger that area. A whitetail may have an 8-inch vital area, but the same area on a moose could be 18 to 24 inches. When writing of the long-range rifle, O'Connor states, "For mountain use the rifle should always be sighted-in for the longest possible range that will not give midrange misses." (The Rifle Book: Second Edition, Revised; Knopf; 1972; page 274).


A "midrange miss" means the maximum rise of the bullet path above line of sight is greater than the area in which the bullet must land at some intermediate distance. If you are sighted for 400 yards and the bullet is a foot high at, say 225 yards, you could totally miss the small vital zone of a deer or antelope at the shorter distance.

This illustrates the mechanics of the maximum point-blank range (MPBR) concept.

Maximum Point-Blank Range (MPBR)

Primed in my youth by O'Connor's practical approach, I jumped all over this MPBR concept when it reemerged in the late 1990s. I beta-tested an exterior ballistics program that, in addition to figuring the usually bullet path values from ballistic coefficient and velocity, had a field to enter "Target Diameter."

This was the same as "vital area on the critter." If you entered a value of 8 inches for example, a graph showed dotted lines at +4 and -4 inches, denoting the vital area in side (path) view. It was easy to spot where the bullet went above or below the vital zone. There was even a little button that, when clicked, automatically adjusted the sight-in values so the bullet's path stayed just within the target diameter value; it told you the longest distance you could shoot without the bullet flying outside the zone. A window at the top of the screen showed how high you needed to be at 100 yards to keep the bullet in the target zone--handy if that's the longest shooting range you have in the neighborhood.

This was where modern technology and O'Connor's practical approach of the precomputer era came together for me. Jack figured out these ranging issues by pulling triggers and putting a lot of bullets downrange. He knew his rifles, the game, and the terrain, and he reached the same decisions we can today with the aid of computers. He even figured out how switching from a shooting bench to his commonly used field position--sitting--affected the trajectory. That's a remarkable achievement.

Maximum point-blank range is, in the concept of targeting a zone or area on an animal, simply the greatest distance that allows the bullet to neither rise nor fall more than one-half the target diameter relative to line of sight. Imagine a long tube whose inside diameter is the same as the vital zone. Your rifle is at one end of the tube, and the other end touches your quarry. When you shoot through this tube, the bullet must not hit the top of the tube at midrange and must clear the far end of the tube by a hair's breadth (see the illustration). If you shoot to a zone or area, MPBR is the length of the tube, or how far you can shoot without elevation correction. That's one less thing to worry about.

I think my fondness of this concept comes not so much from its benefit for long-range shooting but at the other end. I've always had more trouble with closer shots where hold-under is the key. Sighting for MPBR largely takes away this concern.

That computer program I beta-tested evolved into RCBS.LOAD, and it retains that useful MPBR function. However, you can use almost any trajectory program that allows you to set up tables in 25-yard increments. This is sufficient resolution to show you where the bullet achieves a rise and fall of one-half target diameter. It will show where to sight your rifle at 100 yards to achieve MPBR if you do not have access to a longer sight-in facility.

So sighted, you can eliminate some of the classic trajectory concerns, focus more on learning lead and point of impact beyond MPBR, and enjoy the hunt.

You can learn more about the Jack O'Connor Hunting Heritage and Education Center by visiting the website: www

.jack-oconnor.org

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

Tactical Solutions Introduces New X-Ring Takedown SBR Rifle

Tactical Solutions Introduces New X-Ring Takedown SBR Rifle

Keith Feeley of Tactical Solutions sat down with Michael Bane at SHOT Show 2018 to talk about the new X-Ring Takedown SBR .22LR rifle.

Black Hills Evolution of Rifle Cartridge: .308 Win. 175 Gr. Match

Black Hills Evolution of Rifle Cartridge: .308 Win. 175 Gr. Match

David Fortier talks with Jeff Hoffman of Black Hills Ammunition about the evolution of the .308 Win. 175 Gr. Match bullet.

All About .300 Blackout

All About .300 Blackout

The .300 Blackout is here to stay, and we take some time to look at new technology surrounding this cartridge. Next, we pit subsonic rivals against each other before stretching the legs of this CQB round out to 600 yards from a short 9-inch barrel.

Skills Drills: 3-Second Headshot

Skills Drills: 3-Second Headshot

James Tarr runs through the 3-Second Headshot drill.

See More Popular Videos

Trending Articles

The Husqvarna AB. Mauser Series 1100 Deluxe features a European walnut stock, a non-military action, and a two-position  wing-type safety.Husqvarna AB. Mauser Series 1100 Deluxe Rifle Review Rifles

Husqvarna AB. Mauser Series 1100 Deluxe Rifle Review

Joseph von Benedikt - August 19, 2020

The Husqvarna AB. Mauser Series 1100 Deluxe features a European walnut stock, a non-military...

With three versions, three barrel lengths, and three different finishes from which to choose, the Savage Renegauge is by definition a eumatic alternative for a variety of shooting situations.Savage Renegauge Shotgun Review Shotguns

Savage Renegauge Shotgun Review

Steve Gash - July 13, 2020

With three versions, three barrel lengths, and three different finishes from which to choose,...

A half-century in the making, the new DGX Bonded is Hornady's best-ever dangerous-game bullet.Danger Tamed: Hornady DGX Bonded Hunting Ammo Ammo

Danger Tamed: Hornady DGX Bonded Hunting Ammo

Joseph von Benedikt - May 23, 2019

A half-century in the making, the new DGX Bonded is Hornady's best-ever dangerous-game bullet.

The .30-06 Hawkeye Hunter features a 22-inch stainless-steel barrel and a satin-finished walnut stock. Magazine capacity is four rounds. It is well made, accurate, and attractive. This is a fine rifle that is light enough to tote over hill and dale but heavy enough to hold steady for precise shooting in the field.Ruger Hawkeye Hunter .30-06 Review Rifles

Ruger Hawkeye Hunter .30-06 Review

Steve Gash - August 17, 2020

The .30-06 Hawkeye Hunter features a 22-inch stainless-steel barrel and a satin-finished...

See More Trending Articles

More Ammo

Even though muzzle flash has more effect on an observer than a shooter, reducing flash is always a good idea.Muzzle Flash and Other Distractions Ammo

Muzzle Flash and Other Distractions

Allan Jones - November 17, 2020

Even though muzzle flash has more effect on an observer than a shooter, reducing flash is...

The .38 Smith & Wesson was a groundbreaking cartridge. However, maybe it should be a historical footnote..38 S&W Variants and History Ammo

.38 S&W Variants and History

Allan Jones

The .38 Smith & Wesson was a groundbreaking cartridge. However, maybe it should be a...

The Winchester .350 Legend is a no-nonsense whitetail thumper tailored for rifle hunters in the Heartland.Winchester .350 Legend Rifles and Ammo Available Right Now Ammo

Winchester .350 Legend Rifles and Ammo Available Right Now

Payton Miller - August 21, 2020

The Winchester .350 Legend is a no-nonsense whitetail thumper tailored for rifle hunters in...

Starting in the late 1950s, the .338-bore size gained considerable traction — thanks to the .338 Winchester Magnum. Why? Because hunters are often after game bigger and tougher than whitetails. Here's a list of the .338-caliber greats in chronological order in which they were introduced.11 Great .338 Caliber Rifle Cartridges Ammo

11 Great .338 Caliber Rifle Cartridges

Payton Miller

Starting in the late 1950s, the .338-bore size gained considerable traction — thanks to the...

See More Ammo

Magazine Cover

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE Arrow

Buy Digital Single Issues

Don't miss an issue.
Buy single digital issue for your phone or tablet.

Buy Single Digital Issue on the Shooting Times App

Other Magazines

Special Interest Magazines

See All Special Interest Magazines

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Phone Icon

Get Digital Access.

All Shooting Times subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now