Because of bolder and more serious threats to the general public, law enforcement agencies are increasingly turning to compact AR-style carbines and rifles for patrol duty.

SIG Sauer has answered with the SIG 556 and SIG 556 SWAT, which incorporate high-quality carbine features such as a two-position adjustable gas valve, folding stock, multiple vertical forends and Picatinny rails for optics, lasers, and lights.

The SIG 556 departs from the traditional AR by incorporating the charging handle within the receiver, allowing quicker chambering without compromising a good shooting position by unnecessary departure from the dominant shoulder, as is often the case with traditional AR systems.

Thus far, the 556 has been chambered in 5.56x45mm NATO/.223 Remington cartridge. The cartridge dominates law enforcement carbines in most AR platforms, but a call to SIG's customer service center confirmed that SIG plans to introduce its 556 rifle in a 7.62x39mm Russian chambering for 2011.

This is excellent news for agencies faced with more serious threats that require a harder-hitting cartridge and better penetration through media like automobile glass and steel. Of particular benefit is the 7.62x39's low cost. A cursory glance at ammo suppliers such as Midway, Cabelas, and Cheaper Than Dirt shows that the 7.62x39 is half the price of the 5.56/.223 for the same 20-round box.

On average, the 7.62x39 bullet weighs twice that of a .223 and about 35 percent heavier than the heaviest 5.56 NATO rounds. Depending on the amount of powder, a 7.62x39 has a muzzle velocity of 2300-2438 feet per second, while the 5.56/.223 travels at 2750-3800 fps.

The penetration results and kinetic energy on target are evident from testimony in Iraq and Afghanistan. Its history in platforms such as the AK-47 and SKS is also evident in the 1986 FBI Miami shootout and the North Hollywood Bank of America engagement. Both of these events show that perps armed with rifles chambered with this round were able to very easily penetrate car doors and other tough media.

Thirty years later, we are finally starting to even the odds. The 7.62x39 makes perfect sense, because it bridges the gap between the far more expensive .223 and .308 chambering. At approximately $5 per box of 20 rounds, that's 25 cents a round and probably 12-18 cents, if purchased in bulk. This price point will enable officers to practice far more than they normally do. Lower price is a great motivator toward more practice.

I have seen it with hundreds of my students. In today's economy, it is sometimes the difference between practicing and not, considering the .223 is twice the price and the .308 is three times the price. The Russians and the Chinese are pumping out the 7.62x39 by the multi-millions. The AK-47 is by far the most widely used rifle platform in human history and continues to be used by over 75 nations to this day. Ammo is plentiful and abundant.

My first introduction to a centerfire rifle was a $65 Chinese SKS with a beat-up wood stock. Price point and availability were the main reasons. Most young shooters are introduced to a .22 rimfire rifle first, and to a cheap centerfire second. I suspect at least two-thirds of the people reading this have owned or currently own an SKS or AK-47 clone.

Having pointed out the positives of the 7.62x39, we must also look at the negatives. When this cartridge was developed, Communist Bloc doctrine after World War II was to take the enemy out of the fight rather than land a precision shot. There were no SWAT units, and any hit that took the enemy out of the fight was a good hit. Precision was secondary.

The 7.62x39 was not developed for sniper work. Longer cartridges such as the Soviet 7.62x54 were developed for precision work and mimic our 30.06 and .308. The 7.62x39 is a relatively short cartridge case, but packs an effective punch.

Most 7.62x39 ammo is steel-cased and filled with lesser quality powders. The effect on a platform such as the SIG 556 would require a greater vigilance in cleaning and routine maintenance to keep the carbine reliable.

SWAT operators who regularly use Federal, Black Hills, and Hornady match-grade ammo for precision work with the .223 and .308, will find themselves with exceedingly far fewer options in the 7.62x39.  Surprisingly, the best accuracy has been reported with Winchester Wal-Mart bulk packs of 50 and 100 rounds. Wolf steel-cased ammo ranks a close second. Match grade and 7.62x39 are not two words that go together in the shooting community.

Having said that, I think it is possible for SWAT operators and patrol officers to obtain a "general" degree of accuracy with the 7.62x39 by using a precision platform such as the SIG 556 and augmenting the sight picture with a quality laser light such as an Aimpoint, Crimson Trace, or EOTech-type holographic and illuminated sight systems and red/green dots.

Sighting with your ammo brand will be key and so will extensive practice.  With a sugested retail price of roughly $1,700 for the .223 version, the SIG 556 in 7.62x39 fills a needed gap between the more expensive .223 and .308. For agencies and officers with the need for an inexpensive hard-hitting penetrator beyond the .223, the SIG 556 in 7.62x39 is a good option.

Correction: This article initially stated that a 7.62x39mm bullet travels at the same velocity as 5.56 NATO/.223 Rem . This error has been corrected.

Related:

SIG Sauer 556 SWAT Rifle