Best AR-15 Setup For Barrier Penetration
The AR-15 and Barrier Penetration
The AR-15 is an incredibly powerful rifle. It has become a critical part of American gun culture, and many home owners consider their AR-15 one of their primary defenses. However, barrier penetration (both on the battlefield and off) is something to be thought of prior to engaging any target. Some folk are interested in decreasing barrier penetration in an effort to reduce collateral damage. Others are interested in increasing barrier penetration, to improve the likelihood of hitting a moving or hiding target. Regardless of the intention, the fact that AR-15s can be diversely outfitted to increase or decrease barrier penetration, cannot be ignored. This includes the type of ammunition being used.
How Various AR-15 Ammunition Affects Barrier Penetration
There are many more ammunition types for most guns than most people realize. This is also exceptionally true for the AR-15. These are some of the most popular AR-15 ammunition (calibers), and how they impact barrier penetration:
- AR-15 .223 / 5.56 Ammo – This is the standard ammo caliber for the AR-15. Many tests have shown that the AR can fire .223 rounds through a variety of barriers, including vehicle doors, wood, and metal. In fact, there are some tests out there which show .223 rounds can make it through SEVERAL (4 or more even) standard home walls.1*
- Special Operations Command (SPC) 6.8 Ammo – This round was designed by Remington Arms to replace the standard 5.56 NATO cartridge. It requires a few AR modifications, including the barrel, bolt, and magazine. The round was designed to outperform the .223 rounds in a short barrel setup, and provides roughly 44% more energy than the 5.56 rounds, thus also improving barrier penetration.2
- Special Operations COMmand (SOCOM) .458 Ammo – The .458 SOCOM round was developed in response to drug-fueled Somalian warriors who were not affected by the pain of a basic .223 round. The Task Force Rangers who operated Operation Gothic Serpent described many Somalis as impervious to even multiple gunshots and requested a more powerful round. It can be used with an AR-15, provided the receiver is upgraded to support it. This round undoubtedly has a more powerful barrier penetration, but a slower velocity than the standard .223 bullet.3,4
- Bushmaster .450 Ammo – The Bushmaster .450 round requires a modified magazine and upper receiver to work with an AR-15. This round was invented to satisfy big game hunting and provide hunters with one-shot kills at a range of 250 yards.5This round is one of the least likely to be used when there are a lot of potential casualties.
- Beowulf .50 Ammo – The .50 Beowulf round was designed to match the rim of the 7.62x39mm bullet. It is most commonly used for tactical or North American game hunting, including targets as large as the black bear.6Although this bullet has an impressive stopping power, it was created as a low-velocity round. Therefore, it is reasonable to assume landing a shot on an attacker in close quarters combat (such as during a home invasion), will have a higher likelihood of fatality. It is also reasonable that the lower velocity will make a large difference when the bullet makes contact with a barrier; and simple physics dictates each barrier will further slow the bullet’s velocity.
*There are different types of .223 ammunition available, some of which are specifically designed to expand more violently, but still achieve barrier penetration (such as DPX .223 ammunition).7
After reviewing the various types of ammunition available for the AR-15, it is clear that the careful shooter has much control over barrier penetration. Still, there are other factors that can influence the rate of penetration.
Other Factors That Influence AR-15 Barrier Penetration
Some other factors can influence barrier penetration. One of the biggest gun-oriented factors is the length of the barrel. As the AR-15 barrel is shortened, the velocity of the expended bullets decreases substantially. As the velocity of the bullet decreases, so does barrier penetration. It is important to note that 16” is the shortest AR-15 barrel legally allowed by ATF.8This rule applies to AR rifles, not AR pistols, which can be much shorter in barrel length.
Another factor in barrier penetration is the firing distance of the shooter from the barrier. As the distance of the shooter from the barrier increases, the velocity decreases. A bullet is never faster than when it leaves the barrel (muzzle velocity). To rephrase: the closer the shooter is to the barrier, the more likely it will fully penetrate said barrier.
Mathematics also plays a role in a round breaking through a barrier, as certain angles of penetration will make a complete clearing of a barrier more or less difficult. For instance, shooting down a stairway or hallway can create more angled penetration than shooting directly at a wall. Entering a wall at an angle means the bullet has to travel more distance through the wall and has a greater chance of striking other barriers, such as studs, electrical and plumping. Taking the location of civilians, family members, or pets into consideration before firing can prevent an accidental barrier penetration casualty. The depth and material of the barrier also make a difference in potential penetration.
A Few Extra Words About Low-Penetration Rounds
Law enforcement and federal officers follow a bullet standard that encourages barrier penetration. In fact, they believe 18” of penetration is necessary, though 12” is listed as “required.”9 This “standard of code” is not meant to instantly and seamlessly pass through to the civilian, consumer-world. In the case of a home defense, it is absolutely preferable to have different standards. Choosing a low-penetration round for home defense can mean avoiding collateral damage and saving a life. Ultimately, as cool as it is to have a high-powered rifle that can blow a hole through anything, protecting your loved ones, pets, and home is a top priority. Sometimes the lower-penetration rounds is perfect for the situation or defense routine.
Final Tips: Outfitting an AR-15 for Barrier Penetration
In terms of “What is the best AR-15 Setup for Barrier Penetration,” the answer is obviously not simple: the setup and firing practices will change depending upon the type of barriers, the application of the rifle (how it is being used and in what setting), and the number of potential casualties.
Remember, it is absolutely unacceptable to have collateral damage simply to “improve the likelihood” of hitting a moving or hiding target. Certain situations like home defense often means choosing an ammunition that reduces barrier penetration (low-penetration rounds), rather than improve it. Though, using an AR-15 in the battlefield would be more likely to favor high-penetration rounds. Careful thought should be applied to any AR-15 build, namely in terms of how the rifle is meant to be used. Depending upon the intended AR-15 application…the round, barrel length, and shooting style can be modified to maximize efficiency and decrease casualties.
Disclaimer: Be a responsible gun owner, and keep collateral damage in mind when considering things like barrier penetration and ammunition selection!
1Outdoor Hub. Is The AR-15 Appropriate for Home Defense: Penetration Issues. Retrieved from:https://www.outdoorhub.com/stories/2013/11/04/ar-15-appropriate-home-defense-part-one-penetration-issues/
2Revolvy. 6.8mm Remington SPC. Retrieved from: https://www.revolvy.com/page/6.8mm-Remington-SPC
3Teppo Jutsu. What Type of Velocity Can I Expect. Retrieved from:http://teppojutsu.com/458FAQ.htm#_What_type_of_velocity_can_I_expect
4The High Road. 16 Inch Barrel and .223 Velocity. Retrieved from:https://www.thehighroad.org/index.php?threads/16-barrel-223-velocity.737301/
5Frank C. Barnes (5 October 2012). Cartridges of the World: A Complete Illustrated Reference for More Than 1,500 Cartridges. Gun Digest Books. pp. 97
6Cutshaw, Charlie (Jul–Aug 2006). “.50 caliber Beowulf”. Tactical Response. Retrieved January 28, 2013.
7OP Spec training. Short Barrel ARs and Barrier Penetration (Discussing Corbon DPX). Retrieved from:https://opspectraining.com/short-barrel-ars-barrier-penetration-corbon-dpx/
8Daily Shooting. What Is The Legal Barrel Length for an AR-15? Retrieved from:https://www.dailyshooting.com/what-is-the-legal-barrel-length-for-an-ar-15/
9All Outdoor. Home Defense Case: Low Penetration Rounds. Retrieved from: https://www.alloutdoor.com/2015/02/24/home-defense-case-low-penetration-rounds/
About the Author:
Mark Doberman, The Proprietary Gun Smith
The Proprietary Gun Smith is a marksman, expert gun handler, ammunition specialist, survival guru, and lifetime gun enthusiast. He owns (or has owned) nearly every legal firearm and ballistic available, has fired nearly every gun, and regularly consults professionally in the firearm world. He has studied firearms and similar tactical lifestyle for more than 40 years. In addition to writing for ArmoryBay.com, TheProprietaryGunSmith has guest written for more than a dozen other sites and/or magazines in the industry.
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