In our previous articles on this subject, we examined what equipment to add to our rifles, and answered questions from readers. Today I'd like to tackle one of the most controversial issues: what ammunition to select for defensive use. Perhaps inevitably, the quick answer is, "It depends".
There are many factors affecting our choice of ammo. In the case of the AR-15-style rifle, it's complicated because the cartridge it fires (usually the 5.56x45mm NATO round, or the .223 Remington lower-pressure civilian version of that round) is a compromise. It does some things more or less adequately, but seldom does all of them exceptionally well. You can read about why it was adopted here. Briefly, it was initially designed to provide military personnel with a round that would be effective at "typical" combat ranges (100-300 yards), with less recoil and greater controllability (particularly in full-auto fire) than its predecessors (the 7.62x51mm NATO round - .308 Winchester in civilian guise - and, before that, the venerable .30-06 Springfield). It also had to be substantially lighter than its predecessors, so that an infantryman could carry more ammunition and thereby stay in the fight longer without needing resupply.
The initial military-issue round, as used in the Vietnam War, has become known as the M193; a 55-grain bullet traveling at approximately 3,100-3,200 feet per second. The first iteration of the M16 rifle had a rifling twist rate of 1-in-12 (i.e. the rifling made one complete turn every 12 inches of barrel length, or 1.67 times in the 20-inch length of the rifle's barrel). This stabilized the 55gr. bullet enough for accuracy, but allowed it to "tumble" in flesh soon after entering the body. It caused serious wounds in the first few inches of penetration.
Some years later, the military decided that it was desirable to shoot accurately at longer range, and penetrate a typical Soviet-issue steel helmet at a range of up to 600 yards. This led to the development of the M855 round (NATO designation SS109), a 62-grain green-tipped round incorporating a steel penetrator. It offered much better penetration and long-range accuracy, but required a tighter twist rate to stabilize it, and seldom tumbled in flesh. It often made a neat "knitting-needle" type hole, straight through the body, and therefore did not disable opponents as quickly or effectively as the earlier M193 round. (There are numerous combat reports of enemy fighters in Afghanistan and Iraq absorbing 6-8 solid torso hits with M855, but still being able to fight back until blood loss, or a more effective central nervous system hit, took effect. You'll find a more in-depth comparison of the M193 and M855 rounds here.)
Combat experience in Afghanistan and Iraq led to many experiments over the past couple of decades to find a round with greater long-range accuracy and terminal effectiveness, plus greater disabling effect on enemy personnel, to stop them shooting back. Demand was driven by special forces units in particular. Their needs and input led to the development of the Mk. 262 round; a 77-grain bullet with a so-called "Open Tip Match" (OTM) hollow point that was not designed primarily for expansion, but to shift mass to the rear of the bullet, promoting long-range stability. (You can read more about its development here.) A cannelure on the projectile guarded against bullet setback, and promoted fragmentation and tumbling in flesh.
Versions of this round are now produced by several manufacturers in the USA, and by IMI in Israel. It's not ideal for barrier penetration (of which more later), but it offers excellent long-range performance compared to its predecessors, and superior terminal ballistics against human targets. However, such heavy-for-caliber bullets require a tight rifling twist to stabilize them: 1-in-7 or 1-in-8 inches is typical. If your rifling is looser than that (1-in-9 or less), your barrel may not fully stabilize those rounds, resulting in reduced accuracy. Test them in your firearm before deciding whether to buy a good supply of them, and if necessary replace your barrel with a tighter-twist one (something that's easy to do with AR-15-pattern rifles, and relatively inexpensive).
Two other approaches were adopted for military ammunition. The US Marine Corps developed what it calls the Mk. 318 Mod 0 round, designed to penetrate barriers better while remaining capable of inflicting disabling injury on the far side. It's an open-tipped match round like the Mk. 262, although it's 20% lighter. (It appears very similar in its effects to the new FBI round, of which more below.) Meanwhile, the US Army put a lot of effort into improving the standard M855 round, producing the lead-free M855A1. It operates at significantly higher pressures than M855, which has led to reports of increased wear on rifles firing it; but it's claimed to offer better penetration through barriers, and much improved terminal ballistics in flesh. Neither the Mk. 318 Mod 0 or M855A1 are sold on the civilian market, although some examples appear to have "fallen off trucks" and made their way into private hands now and then. For training purposes and outside combat zones, both the Marines and the Army are still using the standard M855 round by the truckload.
Law enforcement requirements have led in a different direction. Cops usually have no choice but to take on a bad guy, to stop him injuring others. They mostly can't choose when, where or how to engage. Therefore, they need a bullet that can both penetrate cover (e.g. auto bodies or glass, doors to buildings, etc.) and inflict disabling injury, to stop a criminal in his tracks. They also typically work at much shorter ranges than the average military engagement, and with innocent bystanders in close proximity; so they need to avoid over-penetration, to reduce the risk to them. What's more, they're not bound by the Hague Convention strictures forbidding expanding bullets, which the US armed forces observe even though the USA was not a signatory to the Conventions.
For general-purpose use, law enforcement has therefore gravitated towards expanding rounds such as Hornady's widely-used TAP (Tactical Application Police) series in various bullet weights. For short-barreled carbines and urban use, many specialist units such as SWAT and hostage rescue teams have adopted bonded soft-point loads. A highly regarded and very knowledgeable ammunition expert had this to say in 2010 about the FBI's chosen solution:
The FBI has completed their testing process and awarded a 5.56 mm ammunition contract for up to $97 million dollars. This award is now public information and appears unique in several ways. Besides being perhaps the largest ammunition contract in FBI history, it is also the first time the FBI has mandated a true 5.56 mm pressure loading, rather than the typical anemic .223 pressure loadings that have generally been marketed to LE agencies. The 5.56 mm load offers approximately an extra 200 fps--helping performance out of short barrel weapons and enhancing function when rifles are dirty or in dusty conditions. The new FBI contract also required that the ammunition be packaged on stripper clips to aid in more rapid loading of magazines. Finally, it is the first multi-award carbine ammo contract for the FBI--both Federal Cartridge and Winchester were judged to offer ammunition which met the contract criteria. Numerous other Federal LE agencies are authorized to purchase off this contract.
The 5.56 mm Federal 62 gr Trophy Bonded Bear Claw (TBBC) bonded JSP load is XM556FBIT3.
The 5.56 mm Winchester 64 gr solid base bonded JSP is Q3313 on stripper clips/RA556B in 20 rd boxes.
Both of these loads are the best barrier blind 5.56 mm loads ever produced for LE use; they offer outstanding terminal performance, even after first defeating intermediate barriers like vehicle windshields.
(Note the similarity - on paper, at any rate - between the Federal load for the FBI and the US Marine Corps' Mk. 318 Mod 0 round, discussed above.)
A brief explanation of terms might be useful before we go any further. The term "bonded", when applied to a bullet, means that its outer jacket and inner core (the former usually copper, the latter usually lead) are engineered to stay together upon impact, ensuring that the bullet remains intact instead of fragmenting, which might result in over-penetration of some fragments and expose bystanders to risk. "Barrier blind" performance means that even after penetrating a barrier such as auto bodies or glass, the bullet will not disintegrate, and will perform substantially as well in human flesh as if there were no barrier at all.
The Federal FBIT3 load for the FBI has also been sold under the SBCT3 designation for non-FBI contracts, and is currently available to civilians through a few suppliers under that designation (here's one that had it in stock at the time of writing). Sadly, it's very expensive (well over a dollar per round), although that's no more than good-quality hunting ammunition costs these days. I have a little of the original FBIT3, and guard it jealously. Nosler makes a near-equivalent round in the form of their .223 Defense Rifle Ammunition, using a 64-grain bonded bullet. The same bullet has been loaded to 5.56mm pressures by other manufacturers; for example, some years ago I tested a version from Beck Ammunition with good results, although it's no longer in their catalog.
Bullets with exposed lead at the tip (such as those mentioned in the previous paragraph) have two potential drawbacks. The first is that they may not feed well in some AR-15-style weapons, because the latter were designed around military-style full metal jacket rounds. Their feed ramps may cause drag against exposed lead bullet tips (particularly in lower-cost, less-well-engineered firearms). Therefore, if you want to use such bullets, it's essential that you test them thoroughly to make sure the combination is reliable. I suggest putting at least 200 rounds downrange through each and every rifle or carbine in which you intend to use them, without a single malfunction, before trusting your life to them. Also, make sure all your magazines can feed them without any problems. Furthermore, you'll need to keep the feed ramps of your weapon scrupulously lead-free, so plan on more intensive and more frequent maintenance and cleaning. That's vitally important.
The second drawback is that such bullets are ballistically and aerodynamically less efficient than pointed styles, with different mass distribution and potentially greater drag. The combination can result in lower accuracy. I've found that my rifles and carbines will deliver 1-2 MOA all day with conventional full-metal-jacket ammunition, but drop to 2-3 MOA, and occasionally even worse, when using soft-point, blunter ammunition such as the Nosler 64gr. bullet or Georgia Arms' economical 55gr. soft-point load. That's not necessarily a drawback in a short- to medium-range defensive environment: a 3"-4" group at 100 yards is still adequate for a head shot, and a 5"-6" group at 150 yards will still fit inside a human target's chest area. The FBI rounds and their law enforcement equivalents were developed primarily for use at those sorts of ranges. For that combat environment, they are sufficiently accurate. For longer ranges . . . not so much.
So, having discussed the options available, what should you choose? Let me start by saying that, if your rifle is chambered for 5.56x45mm ammunition, I strongly recommend that you buy ammunition labeled as such, rather than .223 Remington. 5.56 ammunition is loaded to higher pressures than .223, giving an extra couple of hundred feet per second velocity. (For that reason, don't shoot 5.56 ammo in a .223-chambered rifle, even though it'll usually fit and function just fine. The pressure might be too high for safety, particularly as the rifle gets hot. However, .223 ammo can be fired safely in any 5.56-chambered rifle. Plan your rifle purchases accordingly.)
Selection will largely depend on your budget. For a relatively low-cost solution, the original M193 55-grain bullet will do an adequate job. It also has the advantage for civilian use that it penetrates sheet-rock and building walls relatively poorly, so over-penetration in an urban environment is less likely to be a problem. The M855 62-grain round offers superior long-range performance, but that's something civilian shooters are unlikely to need as much as soldiers - and besides, most of us lack the training and extensive practice needed to take advantage of that accuracy. Also, M193 is more likely to stay in the body of an attacker (and not pass through walls), while M855 is much more likely to over-penetrate and cause potential hazard to people and objects beyond the target. On balance, I recommend M193 as a reasonably effective low-cost solution. (I also stock both M193 and M855 as training ammo, so as not to waste my much more expensive "social use" rounds.) If you want to go to a 55gr. load with less penetration and better terminal ballistics, there's Hornady's 55gr. TAP load, which has an excellent record "on the street"; or there's the Georgia Arms soft-point load mentioned above. Both are loaded to .223 pressures rather than 5.56mm.
(Let me take this opportunity to mention that Georgia Arms offers remanufactured 5.56mm and .223 ammunition, using once-fired cases, at very reasonable prices, perhaps the most economical solution for practice and competition use out there at present. Their "Canned Heat" bulk pack ammunition [packaged in ammo cans, and available in multiple rifle and handgun calibers and loadings] is relatively affordable. I have several hundred rounds of it in my stash as I write these words. No, they didn't ask to be mentioned and they're not compensating me in any way for recommending them - I just like my readers to know about good deals when they're available.)
If you can afford something better, there are several good choices. My round of choice for general-purpose defensive use is the Mk. 262 77-grain OTM. I don't know what my engagement range might be; my location on any given day varies from visiting a city, to driving through the Texas plains. Therefore, I want the versatility of good accuracy and terminal performance anywhere from "up close and personal" to "way out there". I use the Israeli version of the Mk. 262 (you can read a detailed review of it here). Here's a video clip showing its performance in ballistic gelatin. It's particularly interesting to me because the round was fired through a 10½" barreled rifle, the same barrel length as my AR-15 5.56mm. pistol. Despite the short barrel and consequent loss of velocity, the bullet performed very well.
This ammo is expensive, but you get what you pay for. I don't think there's a better general-purpose defensive round out there at present for the AR-15-style weapon than the Mk. 262 or its equivalents (such as, for example, Hornady's 75gr. TAP load). Stocks of the Mk. 262 from any manufacturer are usually limited, due to its expense and military demand for the round. (There are currently a few cases of the IMI version at my favorite supplier.). However, function-test it carefully before adopting it. It's slightly longer than some other 5.56mm rounds, so some magazines and weapons may not load or feed it reliably. Testing is critical before you trust your life to any firearm or round!
For short-barreled AR-15 carbines or pistols in an urban environment, many people prefer 62- and 64-grain soft-point rounds like those used by the FBI and other law enforcement agencies. For use in confined quarters, such as home defense or on city streets, you want as little risk of over-penetration as possible, so those rounds are a decent choice. Another good one is a so-called "plastic tipped" round, like those in Hornady's TAP range. They feed very reliably and, particularly in lighter bullet weights, expand explosively in flesh and are very unlikely to over-penetrate. That's why I carry 55gr. TAP in my home defense AR-15.
There's another option that's been well reviewed by people who know what they're talking about. Barnes Bullets have developed a line of solid copper projectiles, containing no lead. They expand aggressively in flesh, but also offer "barrier blind" performance and deep penetration. Barnes loads them in its own VOR-TX brand of ammunition, and Cor-Bon uses them in its DPX line; some other manufacturers also offer them. John Farnam (whom we've met in these pages before) speaks very highly of the DPX load (I quoted him on the subject back in 2013, when I bought a case of it). It's hard to find these bullets, and ammo using them, in local stores, so you may have to look around online and move quickly when you find some. They're usually quite expensive, but I think they'll serve you very well for short- to medium-range defensive purposes. I carried DPX in my rifles when I lived in a large city (Nashville, TN), and would still gladly do so in an urban environment. However, now that I live in plains country, where longer-range shots may be required, I've switched to Mk. 262 with its better ballistic properties for that purpose. (If anyone wants to buy a few hundred rounds of DPX 62gr., drop me a line. My e-mail address is in my blog profile.)
There are several hunting rounds that will do double duty as defensive rounds. To cite just a few examples, Federal's 62-grain Fusion round or either of Winchester's 64-grain deer hunting rounds are likely to do just as well against two-legged targets as four-legged ones. (You'll have noticed that their bullet weights and types correspond very closely to the respective companies' FBI loads, discussed above - indeed, for all we know they may use the same bullets.) I'd consider myself adequately equipped if they (or equivalents from other ammunition manufacturers) were all I had. You don't have to buy specifically military or law enforcement rounds to be well defended. Just put enough of them through your defensive rifle or carbine to be sure they'll feed and function without any problems before you rely on them. This can be costly, particularly during the current ammo shortage, but don't skimp on the testing. The last thing you want in a real-world defensive encounter is to find out the hard way that you didn't test thoroughly enough, and your rifle is now out of action!
One final word of warning. I know a lot of shooters who have plenty of ammunition, and good-quality magazines, and high-quality rifles and carbines in which to use them: but they don't keep them "ready to go" in case of emergency. I think this is a potentially fatal flaw in their thinking. If you're willing to keep a loaded handgun on standby in case of emergency, why not do the same thing with your rifle? Obviously, you'll not want to have loaded guns accessible to or by unsupervised children: but if you can keep them locked away from over-curious young hands and minds, don't ignore the readiness factor.
I keep a few loaded magazines securely stashed in close proximity to my (equally securely stored) defensive long guns. During periods of increased vulnerability (e.g. while we're asleep at night), a rifle will be near to hand, magazine inserted, ready to chamber a round and go. In more risky situations (such as living in a high crime area where home-invasion-style robberies are not infrequent), I'd probably keep a long gun loaded and ready at all times. A rifle has a lot more "stopping power" than an average handgun, and I want the odds on my side in a fight, thank you very much!
Remember the church shooting in Sutherland Springs, Texas a few years ago? The citizen who took on the murderer and stopped further bloodshed used his AR-15 rifle to do so - but he had to take the time to load a magazine first, before he could intervene. I stand second to no-one in my appreciation of his courage and his willingness to stand up against evil: but how many more lives might have been saved if he'd had a loaded magazine ready to use, and thus been able to respond more quickly? We should learn from that. A defensive rifle - or any defensive weapon - that isn't ready to defend you when the need arises, is not "defensive" at all. It's a contradiction in terms.
In closing, I'd like to mention something I should have said earlier in this series of articles. The 5.56/.223 round, like all modern rifle rounds, is very loud when fired. If you do so without hearing protection, particularly inside a building, hearing damage is almost guaranteed. After years of exposure to close-quarters gunfire, my hearing has deteriorated considerably. Many veterans of military service will say the same thing.
It's worth keeping a set of electronic ear muffs with your defensive firearm, and putting them on (it takes only a second or two) before using it to check on "things that go bump in the night". If you have to shoot, your ears will thank you - and the electronic amplification of sounds will help you track any intruder by the noise he makes (footfalls, voices, etc.). I've used muffs from Caldwell, Howard Leight, Peltor and Walker with good results. They're not very expensive - certainly a lot cheaper than hearing aids later in life! Just make sure you get a set of slimline muffs that won't interfere with your cheek weld against your rifle stock. Thick, heavy muffs may get in the way of that.
A useful adjunct to ear muffs - and something that may minimize damage to your hearing without them - is to use a blast redirection device that throws the muzzle blast forward, instead of letting it spread sideways and rearwards as well. Such devices don't reduce the sound, but minimize its battering impact on your eardrum. (This is particularly useful if you're standing next to a wall when you fire. The bounce-back of muzzle blast from the wall can feel like a physical slap in the face. These devices eliminate that almost completely.)
Two such devices that I've used personally, and can therefore recommend from my own experience, are Midwest Industries' Blast Can and (very recently) Kineti-Tech's muzzle brakes with concussion/redirector sleeves. The latter are more expensive, but offer a double benefit; without the sleeve, the muzzle brake helps minimize recoil and muzzle flip, while with the sleeve fitted, the former benefit is reduced but the sound is redirected. You can use them either way. There are other versions of these devices, of course, which you'll find by shopping around.
Well, there we are. I hope you've enjoyed this series of three articles on the personal defense rifle, and have found something useful in them. If you have anything to suggest, please do so in Comments.