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The Mighty .505 Gibbs

The .505 Gibbs is one of the most serious sporting cartridges in the world.


At first glance, a brawny, classic African express rifle emanates an aura of power and old-time African adventure. Grasping its bolt and shoving a cigar-sized cartridge up the spout only reinforces the magic. As you lift the rifle, it nestles—balanced perfectly—between your hands, ready to stop the charge of a huge, angry beast.

One of the biggest cartridges chambered in African express rifles is the .505 Gibbs, which was developed in 1911 by riflemaker George Gibbs of Bristol, England. Originally, the .505 Gibbs was designed as a rimmed cartridge for use in a double rifle. Changing direction, Gibbs redesigned it as a rimless round to be used in more affordable and increasingly popular bolt-action express rifles. The cartridge soon earned a reputation as being unsurpassed in bringing down unsociable heavyweights, such as wounded Cape buffalo and enraged elephant. In addition, many of the old-time ivory hunters preferred the four-shot firepower of a drop-magazine, bolt-action rifle chambered for .505 Gibbs to the somewhat quicker second shot of a double rifle chambered for anything else.

Published ballistics data shows the .505 Gibbs delivers significantly more muzzle energy than the .416 Rigby, .458 Win. Mag. or .470 Nitro Express. Only when you move up to the .460 Wby. Mag. do you find a cartridge with as much devastating power as the .505 Gibbs.

The test gun was a CZ 550 American Safari Magnum express rifle, a variant of the classic magnum Mauser action with a 22-inch hammer-forged barrel. A Leupold 1.5-5X riflescope was mounted on quick-detachable rings designed for the double-square-bridge’s dovetail bases. That lasted for 11 shots, which included a 2-inch, five-shot group fired at 100 yards with Superior Ammo factory loads. On the 11th shot, the scope flew off and hit me on the forehead before clattering to the ground. Did I mention that the .505 Gibbs has substantial recoil?

Ruined scope rings underscored the evident folly of mounting a scope on a rifle chambered for the .505. Besides, the .505 Gibbs is designed to disrupt the plans of an angry behemoth approaching at close range—not to snipe him from long distance. So, subsequent groups were fired using only the express iron sights at 50 yards instead of 100 yards. The results were gratifying.

Recoil of a .505 Gibbs or any of its peers is something a normal adult human can handle if one uses correct technique. I was, however, not nutty enough to shoot 100 rounds from the bench without some means of mitigating the recoil. The answer was a Caldwell Lead Sled, loaded with four 25-pound bags of shot, which tamed the recoil to an easily managed level. Even then, the .505 Gibbs leaped and bucked as it moved the Lead Sled backward nearly 2 inches on every shot.

To record range data, the test rifle was wired with a strain gauge connected to an Oehler Model 43 Personal Ballistics Lab, which gives peak chamber pressure and related pressure data as well as muzzle velocity via Skyscreens. Initial test groups were fired with factory ammunition from Superior and Norma to reinforce handload pressure limits and factory load accuracy. Moving to handloads, I tested three powders—Accurate Arms MagPro, Hodgdon H1000 and IMR 7828SC—with Barnes and Wood-leigh .505-inch-diameter bullets weighing either 525 grains or 600 grains.

The .505 Gibbs requires a lot of propellant to nudge such heavy bullets to working velocities. Powder charges ranged from 134 grains to about 144 grains, which equates to 50 loads or fewer per pound of propellant. It is not unusual for a big-bore chambering to exhibit gilt-edged accuracy, and the .505 Gibbs is no different. Several loads grouped under 2 inches at 50 yards, despite iron sights and my aging, presbyopic eyesight.

When you uncase a .505 at your local gun club and unleash its thunder downrange, you’ll quickly draw the attention of other shooters who are eager to see and fondle the huge, blunt-nosed cartridges. And, if offered, they will doubtless take the opportunity to touch off a round and feel the pulse-quickening power of one of the most serious sporting cartridges the world has even seen.

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6 Responses to The Mighty .505 Gibbs

Gerald wrote:
June 19, 2013

I was wondering if I could get the load data or get directed to the high end of the scale of pressure and speed out of new cz for the 505 gibbs

PH Augustin K. Chailla wrote:
April 02, 2013

Everyone can say what they like but there is onething though, when it comes to stopping a wounded buffalo, cape buffalo, .505 Gibbs is the best!!

sixtus wrote:
February 24, 2013

Sorry Gordo, the 460 was left in the dust decades ago.. Wildcats beating it, even doubling its power in some cases include 470AR, 500 Asquare, 510 wells, 585 nyati, 600 overkill etc. The gibbs as mentioned has 179grains capacity versus 142 for the weatherby. MAximum loads from a modern strong action like the CZ in the article will allow the gibbs to reach over 2600fps with a 600grain bullet or almost 2000ftlbs more energy than a maxed out 460....

.505 Gibbs wrote:
February 15, 2013

Not exactly true, Gordo. The Gibbs has a greater case capacity than the .460, and with proper reloads it can leave it in the dust.

505 owner wrote:
November 09, 2012

Um, if you are going to comment get the caliber is the .505 Gibbs. There is no such thing as a .500 Gibbs.

Mag Gordo wrote:
November 01, 2012

Althought the 500 is a great round , for all Practical matters the 460 weatherby can surpass it in all respects except bore diameter. The power and authority of the .460 weatherby is absolutely without question. The .460 also has superior long range utility. But, in my opinion for a person who has the penchant and patience for the studied discipline of a heavy rifle the .500 Gibbs would certainly be a superior choice.