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Why Porting a Shotgun Barrel is Effective

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There is no denying the effectiveness of muzzle brakes on rifles. Properly designed, they mitigate felt recoil by redirecting a select amount of the fired round’s gasses backward, upward and/or to the sides, thereby canceling some of the recoil force that would otherwise be sent back to the shooter. Newton’s third law of motion dictates it. But, a more tangible way to feel the effects of a brake is to shoot something like a .300 Win. Mag. with and without one. The reduction in recoil is dramatic—anywhere between 20 and 70 percent, depending on the aggressiveness of the brake’s design. However, the reason muzzle brakes aren’t found on all rifles is because they are not without their drawbacks: If gas is directed too aggressively backward, then muzzle blast is almost unbearable to those nearby. Noise is also increased significantly.

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The same principle occurs with shotgun-barrel porting, but to a lesser extent. A series of small vent holes bored into the top of the barrel are less effective at redirecting gas than a big add-on brake apparatus, but even if a shotgun were to wear an actual brake, it would still be less effective. That’s because centerfire rifles produce vastly higher barrel pressures than shotguns (compare 60,000  to 11,500 psi), and mainly because a rifle’s recoil is derived mostly from its bullet’s velocity (resulting from the pressure of the shell’s gasses) rather than the projectile’s (relatively light) weight, whereas a shotgun’s recoil is derived mostly from the shell’s (relatively heavy) payload rather than its (relatively low) velocity. Neither a brake nor porting can influence projectile weight, but they can influence gasses as they exit. This means that despite marketing hype, quality shotgun-barrel porting commonly reduces the shotgun’s recoil somewhere between 8 and 15 percent.

In practical terms, the more powerful the load, the more effective barrel porting can be. So, if you shoot a light load, don’t expect to feel a huge difference with porting. But, if you shoot a 3-inch magnum, 1,450 fps, 12-pellet buckshot load, you may notice a reduction. Mathematically, if that 8-pound shotgun generates 47 ft.-lbs. of free recoil energy, you can expect a 5- to 6-pound reduction. Frankly, that’s not all that much.

What’s more compelling, at least academically, is the reduction in muzzle rise porting offers. Although figures are quite subjective depending on the gun, load, barrel length and the shooter, muzzle-rise reductions up to 50 percent aren’t unheard of. Less muzzle flip means quicker follow-up shots. How much quicker? Fractions of a second, for experienced shooters.

While that might not “wow” you, quicker is still quicker, right? Less felt recoil is still less felt recoil. Fact is, every shotgun would be ported if it weren’t for a couple of main drawbacks.

… So, if you shoot a light load, don’t expect to feel a huge difference with porting. But, if you shoot a 3-inch magnum, 1,450 fps, 12-pellet buckshot load, you may notice a reduction.

First, anytime gas from the shell is directed closer to the ears rather than linearly out the barrel, the risk of hearing damage can be increased. The exact decibel-level increase, or any increased risk percentage, is nearly impossible to quantify. But, in an actual home-defense emergency, a little extra noise from a shotgun fired inside a home will be violent and deafening with or without porting. It’s not something I worry about.

More concerning is the added muzzle flash that’s directed vertically from the barrel. If the gun is fired from the shoulder with the barrel extended out normally, the momentary flash-fire of gas as it’s expelled from the vents is negligible in daylight and moderately distracting in dark environments. (Your night vision will be temporarily hampered with or without porting.) But, many self-defense experts caution against barrel porting on any self-defense gun that might be fired from awkward positions. If the top of the barrel happens to be inches from your eyes when the trigger is pulled, the hot gasses could, at worst, permanently blind you. The chance of this happening is small, but it exists.

So, the question is: Is a 12-percent reduction in recoil (using the average) and perhaps a 50-percent reduction in muzzle rise worth the small risk of being distracted or (worse) injured by venting gasses?

In competition, where time splits between shots can mean the difference in a winner’s purse or a long ride home, the answer is an emphatic “yes!” For competitive shooters, there’s no real downside. But, home defenders must consider conditions that are unpredictable and uncontrolled where anything could happen.

Other home defenders might consider their choice of firearm before deciding. Mossberg’s wildly popular, but diminutive (14-inch barrel, 5.25-pound) Shockwave exhibits massive recoil and muzzle flip, so anything the shooter can do to lessen that is, at least on paper, a good thing. Carlson’s Choke Tubes company offers a ported replacement barrel for the Shockwave for $249. However, for all the reasons the porting’s effectiveness is enhanced on the Shockwave, so too are its disadvantages; muzzle flash caused by still-burning powder is exacerbated, as are the chances of waving that shorter barrel near your face. But boy, porting does indeed make this gun more manageable.

Mag-na-Port’s Pro-port shotgun service utilizes Electrical Discharge Machining (EDM) to remove metal in a surgically accurate fashion. This precision porting method leaves no tooling marks, burrs or edges to grab the shot wad. It’s superior to drilling. Mag-na-Port charges $99 for its service. Or, if you don’t wish to pay for custom EDM barrel porting, you can simply buy a ported choke tube from Carlson’s or elsewhere that can reduce muzzle flip by approximately 40 percent and felt recoil by around 8 percent. 

Shotgun barrel porting has its pros and cons. If you shoot often for practice, are recoil sensitive, your shotgun/load of choice produces severe felt recoil and muzzle flip or you just prefer the best-performing gun money can buy, consider barrel porting. But, if you are not significantly affected by your shotgun’s recoil and are not concerned with shaving a few milliseconds between follow-up shots, your non-ported shotgun is more than adequate.

Article by JEFF JOHNSTON

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