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Mini Compendium of Big Bore Cartridges

by Daniel McCarthy
© 2004

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.