Big Bore Compendium – Summary & Conclusion

A table for use in comparing the various big bore cartridges discussed in this article is shown below. The velocities listed are generally the upper limit of what a normal human would want to fire from these rounds, although most of the cartridges will permit even more velocity without excessive pressure, but there are few humans who would want to endure the rather punishing recoil that results.

Cartridge Bullet Diameter (inches) Bullet Weight Velocity (f.p.s.) Typical Weight of Rifle Recoil Energy (ft. lbs.) Recoil Velocity (f.p.s.)
505 Gibbs .505 525 2350 12 pounds 84 21
505 Gibbs .505 600 2400 (with reloads) 12 pounds 106 23
500 Nitro Express .510 570 2150 11 pounds 77 21
500 Jeffery .510 535 2400 10.5 pounds 92 23
500 Jeffery .510 570 2400 (with reloads) 10.5 pounds 103 25
500 A-Square .510 600 2400 11 pounds 107 25
550 Express .550 600 2400 11 pounds 107 25
550 Express .550 650 2200 11 pounds 98 24
550 Express .550 700 2100 11 pounds 101 24
550 Magnum .550 600 2500 12 pounds 113 24
550 Magnum .550 650 2400 12 pounds 112 24
550 Magnum .550 700 2300 12 pounds 113 24
577 Nitro Express .585 750 2050 14 pounds 95 20
585 Nyati .585 750 2300 13 pounds 129 25
577 Tyrannosaur .585 750 2500 13 pounds 172 29
600 Nitro Express .620 900 1950 16 pounds 104 20
600 Overkill .620 900 2400 14 pounds 189 29
700 Nitro Express .700 1000 2000 18 pounds 115 20

From this table it is easy to see that increasing the velocity of a heavy bullet increase recoil very substantially. Personally I find anything with recoil energy above 100 pounds difficult to shoot. And when recoil velocity exceeds 25 f.p.s., the recoil has a very sharp jab to it. But with the appropriate stock design and some mercury tubes in the stock, the edge can be taken off the recoil so that pulling the trigger does not cause quite as much physical trauma as having an auto accident.

Actions, etc.

The most difficult portion of a big bore custom rifle project is selecting and paying for the appropriate action. Some cartridges, such as the .585 Nyati and .505 Gibbs, and 600 Overkill are best built on a magnum mauser action which can cost from $2800 on up for the action alone. Actions suitable for at least some of the cartridges listed above are available from Granite Mountain Arms of Prescott, Arizona, David Gentry (www.gentrycustom.com) of Belgrade, Montana, Hartman & Weiss of Hamburg, Germany, Karl-Heinz Ritterbusch of Germany, Reimer Johannsen of Germany, Gottfried Prechtl of Germany, Vektor Arms of South Africa, Waffenfabrik Hein (www.rifleactions.com), the CZ550 action from Brownell’s catalog, and the P14 Enfield action. Some of the cartridges, such as the 500 Jeffery, 495 A-Square and 550 Express will fit on a standard sized action such as a Winchester model 70 or Mauser 98 after extensive remodeling.

Barrels and reamers for these cartridges are available on a custom order basis from many of the usual sources. Dies for most calibers are available from CH4D (www.ch4d.com) in Ohio, RCBS in Califonia (through www.huntings.com), or Redding (www.reddingreloading.com) in New York. Bullets may be obtained from Woodleigh (distributed by Huntingtons and Midway in the USA), Barnes, Hawk, and others.

By its nature, any encycolopedic writing such as this is abridged and therefore incomplete. To the extent that I have failed to mention any relevant manufacturers, products or gunsmiths, I offer my apologies, because anyone who provides a product or service to the big bore market is advancing our sport.

Recoil Control and Other Concepts

Big bore rifles have gotten a reputation for delivering punishing recoil at levels that will cause concussions and break collarbones. While a lightweight big bore rifle with a poorly designed stock will be painful to shoot, some relatively simple measures can be taken to significantly tame the recoil of big bore rifles and bring their recoil levels within the reach of ordinary shooters. These are discussed below. There are also passages below covering miscellaneous topics related to big bore cartridges.

Muzzle Brakes
A well-designed muzzle brake assists in dissipating expanding gases produced when gunpowder is burned. Ordinarily expanding gases will travel out of a barrel directly away from the shooter, propelling the rifle rearward into the shooter’s shoulder. A muzzle brake can be used to redirect a portion of those gases laterally so that there is not quite so much gas pushing the rifle rearward into the shooter. A muzzle brake can also be designed with an internal chamber so that gas, which exits the muzzle of the barrel and hits the front of the muzzle brake chamber, tends to push the rifle away from the shooter, thereby reducing recoil. Finally, muzzle brakes can reduce muzzle rise during recoil, making the rifle more comfortable to shoot.

Mercury Recoil Reducers
Mercury recoil reducers are metal tubes partially filled with mercury. They add weight to a rifle, and adding weight always reduces recoil. But more importantly, when a rifle with a mercury recoil reducer begins to travel rearward under recoil, the mercury will tend to remain stationary in its tube due to inertia. But after the rifle has moved some small distance, the mercury tube, which is moving with the rifle stock, hits the stationary mercury. The stationary mercury absorbs some of the energy of the rifle’s recoil, and also slows down the velocity of the recoil. The net result for the shooter is that the recoil feels less swift and sharp as the mercury reduces the bite of the recoil.

Recoil Pads
There is no question that not all recoil pads are created equal. Some look good but feel as hard as steel when the trigger is pulled, while some absorb recoil quite nicely. For heavy recoiling big bore cartridges, reliance on traditional recoil pads will only make the shooter uncomfortable. Some better performing recoil pads include the Pachmyr F990 and the Answer System recoil pad. Personally I think that the Pachmyr Old English recoil pad is inadequate for anything above .458 caliber.

Second Recoil Lug
Generally cartridges above .458 Winchester Magnum require a second recoil lug on the barrel in order to spread out the transfer of force from the barreled action to the stock and reduce the chance of splitting the stock. Adding a second recoil lug to a barrel is not expensive and should not be skipped in any big bore project.

Cross Bolts
As a rifle moves rearward during recoil, the recoil lug exerts a force longitudinally on the rifle stock. That force tends to push the wood of the stock outward laterally much the way an axe splits a piece of firewood. Cross bolts in the stock tend to keep the grain of the wood compressed and reduce the ability of the wood to move, also reducing the chance that the wood will split.

Primers
Field experience by many shooters has shown that Federal 215 and Federal 215 Match primers give the best ignition for the heavy powder charges of big bore cartridges. Federal makes a hotter primer called the F216 for its 470 Nitro Express factory loads, but will not sell the F216 to the public.

Conclusion

For the person wanting the biggest bolt action dangerous game rifle that there is, the Hambrusch .700 NE has no competition. A more affordable alternative with nearly as large a bore diameter is found in the 600 Overkill, which can be constructed for a little more than US$3000 using a CZ550 action. Most rifles fall between these two extremes and at this time an excellent big bore bolt action rifle suitable for use on dangerous game can be built for between US$10,000 and US$20,000.

Some of the more practical alternatives for the reloader seeking maximum power are found in the .550 Magnum, .550 Express, 500 A-Square and 495 A-Square which are all based on .460 Weatherby brass which is plentiful and relatively inexpensive. For the traditionalist, a 505 Gibbs is an option and it is certainly attractive in some of the fine rifles that are available. A .500 Jeffery, when assembled by a expert big bore riflemaker, is also a sound choice. The other cartridges each have their place, depending on the shooter’s preferences. No matter which of these the reader may choose, I can assure you that the .375 H&H will have absolutely no felt recoil after a range session with your new big bore.