by Tiger McKee The original concept of the SPR (Special Purpose Rifle) began with the military searching for an upper assembly that could be snapped onto a standard M4 carbine lower. This upper would provide a lightweight package with sniper grade accuracy at extended distances- using match grade ammo - for small special-forces groups operating in the field. This concept was originally called SPR for Special Purpose Receiver. The Army Marksmanship unit, working with 5th Group Special Forces, experimented with various combinations of barrels, uppers, and scopes. Initial testing revealed that to take full advantage of the upper's accuracy it needed to be mated to a lower equipped with a match trigger assembly, one that would provide semi and full auto fire, a full-length stock for a better fit, and a few other tweaks. The Special Purpose Receiver became the Special Purpose Rifle. The first complete rifles were evaluated at Thunder Ranch, Texas in 2000. These tests revealed a few final modifications needed to complete the concept. With the specs finalized a production run of one hundred rifles were assembled for field-testing. These rifles ended up being "tested" in 2001 during Operation Enduring Freedom. They were extremely effective. Eventually the SPR became the Mk12, which after a few more modifications became the Mk12, MOD 1. (For a detailed account of this process see the book "Black Rifle II.") There is no doubt the AR is the most popular platform in the U.S. In the last few years the number of parts for the AR have increased, improved, and evolved to where the AR is just as accurate and effective as any bolt gun out to 600 yards or more, but with many advantages over the bolt action. The AR is a familiar platform, ergonomic and easy to use. The semi-auto provides immediate follow-up shots. The ability to rapidly engage multiple targets efficiently is always a big plus. Reloads are easy. Although it can be built for a variety of calibers, the 223/5.56 is extremely versatile, has light recoil, and the range of bullet weights and designs available will cover almost anything you might need. There are a variety of optics for the available for the AR platform, with many calibrated for specific calibers and bullet weight. So, with all these things going for it I finally broke down and decided to build a .223/5.56 SPR for precision work. My ultimate goal is to build an SPR with excellent accuracy, but also a rifle that will work for defensive purposes as well. I don't need to engage targets at eight hundred yards, but if necessary I want to be able to put 'em in a dime at one hundred yards. At the same time I want to a rifle to put rapid hits on a threat at ten yards or closer, an event I'm more likely to face. The next two sections of this series will get into parts selection, tools necessary to assemble a reliable AR, and the end results on the range. In the meantime, if you're considering a precision rifle, start thinking about the AR platform. Tiger McKee is director of Shootrite Firearms Academy, located in northern Alabama. He is the author of "The Book of Two Guns," writes for several firearms/tactical publications, and is featured on GunTalk's DVD, "Fighting With The 1911 - http://shootrite.org/dvd/dvd.html Website: www.shootrite.org http://www.facebook.com/pages/Shootrite-Firearms-Academy/156608611038230?ref=ts