By Chuck Hawks
Recoil is generally expressed as "free recoil" and measured in foot-pounds of energy. Free recoil means that the rifle is allowed to move backward unrestrained after being fired. If your shoulder restrains the rifle's rearward motion, then your shoulder must absorb the energy generated by the recoiling rifle. Bummer!
Recoil is measured in something called a recoil pendulum, or calculated by mathematical formula based on Newton's physical law that says for every action there is an equal and opposite reaction. MV = MV (mass times velocity equals mass times velocity), the momentum must be equal on both sides of the equation. Newton's law explains why rocket motors are able to propel the space shuttle into orbit, and why guns kick.
The principle factors that must be considered to calculate recoil are bullet weight (mass), bullet velocity, powder charge, and rifle weight (mass). The mass times the velocity of everything ejected from the muzzle of a rifle (principally the bullet and powder gasses) will be equaled by the mass times the velocity of the recoiling rifle.
In 1909, the British Textbook of Small Arms stated that 15 ft. lbs. of free recoil energy was the maximum allowable for a military service rifle. (The standard British .303 Lee-Enfield infantry rifle was below that figure, as are most service rifles to this day.) The 1929 edition of the same textbook stated that recoil velocity should not exceed 15 fps; above that velocity a gun-headache was very likely to occur. These figures remain practical maximums for the modern hunter.
About 15 ft. lbs. of recoil energy represents upper limit of the average shooter's comfort level. Above that recoil becomes increasingly intrusive. The majority of authorities seem to agree that recoil of over 20 ft. lbs. is likely to cause the average shooter to develop a flinch, which is ruinous to accuracy.
The effects of recoil are cumulative. The longer you shoot and the harder a rifle kicks, the more unpleasant shooting becomes and the more likely you are to jerk the trigger or flinch.
The free recoil velocity is how fast the gun comes back at the shooter. The faster a gun comes back at you the more it hurts. This is because your body has less time to give with the recoil.
You have probably heard about the "long, slow push" touted by some big bore fans as opposed to the "sharp rap" supposedly delivered by high velocity cartridges. Recoil velocity is a real, measurable effect. However, the "long slow push" appears to be a myth. Both my own personal experiences with a reasonable range of rifle calibers from .22 LR to .458 Win. Mag. and a quick perusal of the Rifle Recoil Table will show that the recoil velocity tends to increase as the recoil energy increases.
The following examples of recoil energy and velocity are all measured in 8 pound rifles. (Caliber [bullet weight, muzzle velocity] = free recoil energy & free recoil velocity.)
In the typical examples above, as the bullet weight goes up the muzzle velocity (MV) goes down; but the recoil energy and recoil velocity both continue to go up. The heavy bullets at relatively low velocity do not deliver a "long slow push," they deliver a progressively harder and faster blow to the shooter. Note that the high velocity .270 with its 140 grain bullet has a recoil velocity of only 11.7 fps, while the relatively low velocity .450 Marlin with its 350 grain bullet at 2100 fps has a recoil velocity of 17 fps!
Rifle weight plays an important role in determining the amount of recoil delivered to the shooter's shoulder. For any given caliber and load, a lighter rifle kicks more than a heavier rifle. Which is why I avoid ultra-light hunting rifles. Here are a couple of examples showing the effect rifle weight has on recoil energy and velocity when shooting the exact same load.
You can do your shoulder a favor by avoiding lightweight magnum rifles and "guide guns." If you plan to do much shooting, get standard weight rifles. The "Rifle Recoil Table," which can be found on the Rifle Information Page, has recoil energy and velocity figures for a great many rifle cartridges fired in rifles of typical weight.
This is all well and good for theoretical models, but in reality the shooter's perception of recoil is influenced by the free recoil energy and the free recoil velocity his or her body must absorb and the shooter's pain threshold plus other factors. Some of these include stock fit, the size and shape and consistency of the rifle's recoil pad or butt plate, muzzle brake (if any), and even action type in the case of a gas operated autoloader. Muzzle blast subjectively seems to increase recoil, although it has no actual bearing on the free recoil. If the shooter is only wearing a light shirt the kick will feel worse than if he is wearing a heavy jacket or padded shooting vest.
Some of the factors that influence subjective recoil can be controlled. Wear a padded shooting vest at the range, and always wear ear protection when shooting. Have your rifles fitted with efficient recoil pads if they were not supplied that way by the manufacturer.
When shooting, pull the rifle firmly against your shoulder. Do not let it get a running start at you. Severe bruising or even a broken collar bone can result from holding a hard kicking rifle (especially something like a .375 or .458 Magnum) away from your shoulder.
Keep range sessions with powerful rifles short. Fire a group and then give yourself a break. When testing a powerful rifle I like to alternate between it and a mild kicking rifle (like a .243). I shoot a group with one rifle, then a group with the other. I seldom shoot more than one box of (20) cartridges through a hard kicking rifle during one range session, and half a box is better.
There are devices that can be added to rifles to reduce recoil. Muzzle brakes are one such accessory, and they come standard on some hard kicking rifles. They reduce recoil by redirecting the escaping powder gas to the side and rearward. Everything that leaves the barrel adds to the recoil, which in the case of a rifle is the bullet and the gasses that propel it down the barrel. (A sabot, should one be used, also adds to the recoil.) The jet effect of the escaping powder gasses makes up about 25% to 50% of the total recoil of a modern rifle. An efficient muzzle brake can reduce the actual recoil by about 20% in some cases (the figures vary widely). See my article "Muzzle Brakes" for more on this subject.
The dark side of muzzle brakes is that they dramatically increase muzzle blast. In fact, with every shot they typically cause permanent hearing loss even if the shooter is wearing normal ear protection. The effect on unprotected bystanders is even worse. For this reason muzzle brakes are not appropriate for most hunting rifles and most hunting conditions. Many guides and outfitters will not permit a sport to use a rifle equipped with a muzzle brake. Some African countries prohibit their use by law.
Another recoil control device is the mercury filled or weight and spring loaded anti-recoil tube. These devices are usually mounted in the buttstock of a rifle or shotgun and help to reduce perceived recoil in two ways. First, they add weight, which actually reduces recoil. (The same benefit can be achieved by packing the butt with lead shot.) And second, the mercury or the spring loaded weight in the tube (depending on the type of tube installed) moves forward under recoil as your body is driven back, temporarily storing some recoil energy. As your body begins to recover from the rifle's recoil by moving forward again, the mercury or weight is moved back to its starting position, dissipating the stored energy. The net recoil energy is the same, but its peak amplitude is lower and its duration is longer. The subjective result is perhaps a 20% reduction in recoil.
Gas operated semi-automatic rifles also reduce perceived recoil by spreading it over a longer period of time. Rifles like the Browning BAR and Remington 7400 are an excellent choice in powerful calibers and for recoil sensitive shooters. The Remington is available in standard calibers up to .30-06; the Browning is also available in standard calibers, and adds 7mm Magnum, .300 Magnum and .338 Magnum to the list.
Always take pains to see that any new rifle has a stock that fits you. A length of pull that is too short; a small or hooked ("rifle") buttplate; excessive drop at comb and heel; or a comb that it too high, particularly if it is also thin, can all be poison. A swell example of a very poorly designed rifle stock (from the standpoint of efficiently minimizing recoil) is the famous flintlock "Kentucky" rifle. These traditional stocks incorporated most of the negative features mentioned above. Obviously, these stocks were not designed for powerful rifles!
The modern classic stock, which features a nearly level comb designed to transmit recoil in a straight line to your shoulder and minimize muzzle jump, tends to keep the comb from rapping the shooter's cheek bone. The Weatherby magnum stock uses a Monte Carlo comb with a cheekpiece that slants down from back to front (rather than down from front to back like a Kentucky rifle) to move the comb away from the shooter's face during recoil. Both of these designs handle heavy recoil pretty well.
Rifles in calibers that generate heavy recoil, from about .375 H&H on up, should have their forward sling swivel mounted below the barrel, forward of the forearm. This is done to protect the shooter's fingers. With really hard kicking rifles the forward sling swivel, if mounted to the forearm, can injure the hand when the rifle slams back.
Thumbhole stocks should be avoided on hard kicking rifles. They are not only ugly; they can be dangerous. The recoil of a powerful big bore rifle exceeds the strength of the thumb joint; firing such rifles can hyper-extend, dislocate, or even break the thumb.
A special stock designed specifically to minimize the effect of recoil is the A-Square Coil Chek. This stock was designed as a cooperative effort between a weapons system engineer, an orthopedic surgeon, a muscle internist, and an anthropologist specifically for rifles chambered for magnum and powerful, big bore (over .40 caliber) cartridges.
It features an exceptionally wide butt pad that distributes recoil over a large area and helps to support the rotator cuff muscle. The Coil Chek stock also incorporates a specially shaped pistol grip that helps the shooter's master hand to retain a secure grip on the stock during recoil; this allows the right arm to absorb some of the recoil energy. The comb of this stock is designed to fully support the shooter's face and retain it in the same location on the stock during recoil to prevent violent snapping of the head and neck, minimizing the possibility of headache, whiplash, neck injury, or retinal separation. The forearm of the Coil Chek stock is designed so that the thumb and fingers of the shooter's hand do not slip or lose their grip during recoil, thus also helping to absorb and control recoil. This stock is said to reduce perceived recoil by up to 50%.
Whatever the approach, recoil is an unavoidable by-product of shooting and must be managed. Proper bullet placement is the principle factor in killing power, and consistent bullet placement is not possible if the shooter jerks the trigger or flinches because of his or her rifle's recoil. The best advice I can give is to select a rifle in a caliber that is within your basic recoil tolerance, and then further reduce the subjective effect of its recoil by all the appropriate means possible.
Copyright 2003, 2016 by Chuck Hawks. All rights reserved.