After Vietnam, the Marines wanted more accuracy and better long-range penetration from the 5.56mm on Soviet personnel armor at extended ranges. In order to accomplish this, the Marines specified a 20-inch heavy barrel, a 1:7 twist, and a 62-grain steel core bullet for the M16A2. They got more accuracy, and a weapon that was nearly three pounds heavier than the original M16, but any tumbling potential was gone. The 5.56 M16A2 punched a 5.56mm hole going in and the same size hole going out; it was a much less devastating weapon. In Mogadishu, our troops, armed with M16A2s, faced the slightly built Somali population, whose people tend to have a very low muscle mass. This gave the 5.56mm less opportunity to inflict severe wounds compared to the same round impacting a heavily muscled person. Also, many Somalis were high on the local drug “khat,” which reduced their sensitivity to pain. These factors combined to reduce the ability of our troops to instantly incapacitate their attackers.
Fast forward to Afghanistan. Our troops have been faced with opponents with physical features similar to the Somalis and who have large amounts of locally grown opium available to them. The 20-inch barrel of the M16A1 and A2 was reduced to 16 inches on the now generally issued M4 Carbine, thus dropping velocity a couple hundred feet per second, perhaps more, over the A1 and A2 rifles. On top of that, engagement distances over desert and mountain terrain were much greater than encountered in previous battles involving the M16. The 5.56mm round simply ran out of gas. Going from the 62-grain ball round to a 77-grain Black Hills boat-tail hollowpoint has, according to my Special Forces source, served to resolve those issues without the need of switching to the 6.8 SPC or other round.
The 55-grain 5.56mm round, particularly when fired out of a 20-inch barrel, should prove quite effective when fired within its 300-meter effective range. I have searched for, but haven’t found, someone making a 1:14 twist AR barrel and upper, and I would love to try one with 5.56mm ammo. That combination should prove to eliminate the need for expensive expanding ammo. Even though I can’t get one, I am still satisfied with ball 5.56mm performance out of my 20-inch rifle and, for that matter, my M4 in general. For duty use I am required to use controlled-expansion rounds like the Hornady TAP, which isn’t an issue, since my agency provides the ammo and under our current conditions law enforcement must be concerned about the potential for unintended collateral damage. Following collapse, though, that issue tends to disappear, both for civilians and cops who may find that their agency has run out of their limited supplies of controlled-expansion ammo and ball ammo is all that they have left. It also won’t matter for officers who have abandoned their posts to protect their families.
When it comes to larger-diameter rounds like the .30 Carbine, 7.62×39mm, and bigger, there are few folks who bother purchasing controlled-expansion rounds unless they use these cartridges for hunting. Often, ball rounds can be purchased on sale in bulk amounts of 500 or so at a very low per-round cost. A bargain it may be, but it’s here I’ll throw out three cautionary issues.
Bulk purchase cartridges in calibers used by former Soviet Bloc countries are often corrosive in nature. In the past, some of these rounds have been labeled as “low corrosive” or with some other such misleading term to boost their sale. There is no such thing—corrosive is corrosive. The corrosive component of such rounds is the primer, specifically primers using the old fulminate of mercury to prompt the power ignition, rather than more modern materials like lead styphnate and others. The only way to really clean the weapon and stop corrosion once these rounds have been fired is to strip the weapon and flush with hot soapy water like you would a blackpowder weapon, or to use a cleaning agent designed to remove the mercury fouling.
When these rounds were used in bolt-action weapons, cleaning was relatively simple and only the barrel itself needed attention. In guns like the AK-47 or SKS, though, not only the barrel needs to be cleaned, but also the gas piston system and housing. No thanks, count me out. Remember, the former Soviet Army didn’t care what they shot out their guns. Those firearms were so cheap to manufacturer that, if corrosion became a problem, they would make a new one or replace the corroded parts. Or maybe they didn’t even concern themselves. You don’t have that luxury. Pay a few more bucks and get non-corrosive ammo from a trusted source.
My second concern about bulk ball ammo concerns the powders they use. Cheap, Russian-manufactured 5.56mm ammo I’ve fired uses cheap powder that shoots dirty. The last thing a direct-gas AR-15 needs is more powder fouling blown into the action. Before you buy any of it in bulk, try some out in small quantities. The increased fouling doesn’t bother an AK or SKS, but I promise you it will eventually make most ARs unhappy.
There is some disagreement on this next point, depending on what manufacturer or armorer you ask, but I tend to play it safe, and so I’ll tell you not to use steel-cased ammo in an AR. It is, without a doubt, harder on the extraction system, which was designed to work with brass. I don’t believe this to be an issue on the robust AK-47, which may have taken the use of steel-cased ammo into consideration in its design, as brass was in short supply near the end of WWII.
There are other issues with steel ammo beyond the extractor. Some of the cases that are polymer coated to be easier on extractors can have that polymer begin to soften in rapid fire as the gun heats up. Some brands used zinc-washed cases to protect from steel to steel contact without the possibility of gumming things up; Hornady uses zinc on steel on its low-price practice ammo line. We used this ammo and Russian-made Silver Bear (not to be confused with Silver State Armory) zinc-plated ammo at my former sheriff’s office qualification back when brass ammo was in short supply during the start of the Iraq war. The ammo is fine until it’s opened and left exposed to the air for awhile, but even when kept in our climate-controlled armory, these rounds developed a powdery white oxidation on the cases. I refused to run the stuff through my personal rifle during qualification. Maybe it wasn’t an issue, but I didn’t want to risk it.
In summary, purchase only non-corrosive ball ammo, brass cased, and of a known brand or source for your defensive stores. If you have some of the really el-cheapo stuff on hand or you just want to plink, use it (not the corrosive stuff though) and then tend to the cleaning of your guns. For pistols, I also avoid steel-cased stuff, but Speer’s aluminum-cased Blazer ammo is satisfactory. Aluminum is actually softer than brass and won’t harm extractors, although the aluminum case dents a little more easily than brass if you drop it on a hard surface. Blazer has been time tested and used by police agencies to save funds during qualifications for at least 20 years. If you can find it, get it. The same cautions goes for shotguns. There are some cheap brands of foreign manufactured shotshells that use steel for the cartridge case heads instead of brass. Do what you want, but I won’t use that in my defensive shotguns, especially ones that don’t have Mil-Spec parts.