Now that Jeff Creamer of SB Tactical has helped us lay out the legal requirements of building an AR-15, it’s time to put a sample AR-15 modern pistol together.
The Upper of Your AR-15
I started with the upper, as I already had a 7.5-inch AR-15 shorty upper from Kinetic Concealment. Originally known as the “Scorpion,” the Bobcat upper makes a great starting point. While the lower receiver is important, it is the upper that makes the gun, in my opinion.
Short AR-15 uppers that run with total reliability are a relatively new thing. As recently as 10 years ago, that simply wasn’t the case. A lot of shorter AR-15s were “jam-a-matics.” Those that did run really didn’t like getting dirty and needed cleaning much sooner than an M4 carbine or AR-15 rifle. Fortunately, things have changed, and uppers like the KC Bobcat run very reliably. In fact, I have had zero malfunctions with it.
Priced at $299, the KC Bobcat features a 7.5-inch barrel and .223/5.56 Wylde chamber. Twist rate is 1×7. While the current Bobcat features a Parkerized barrel, the unit I have was left in bright stainless. A 3.5-inch aluminum barrel extension compensator caps it off. A sleek 10-inch, free-floating keymod handguard finishes the package. Two keymod attachments are included. I used an existing hard-chrome bolt carrier group to complete the operating system. A KC Ambi charging handle was included with the Bobcat upper.
Finishing AR-15 Components
I installed a set of XS Sights: the excellent Flip-Up Tritium front stripe with CSAT A2 aperture rear. They are lightweight and keep the profile of the finished arm low when folded. They also keep the overall weight manageable.
In order to save additional weight, I selected an American Tactical Omni Hybrid polymer lower receiver. The Omni shipped with trigger and internal parts in place. As per the legal requirements, it was titled as “Other” when transferred.
The pistol-stabilizing brace came from SB Tactical, of course. I chose the skeletonized SOB pistol-stabilizing brace, as it weighs in at only 7.1 ounces.
To complete the package, I added a Tactical Link Stealth Single Point QD Tactical sling in Dark Earth. The lightweight, simple design is ideal not only for carrying the completed pistol but also for applying tension when holding it straight out, which stabilizes it during firing.
Shooting an AR-15 Pistol at the Gun Range
I took the completed pistol to the range with SIG Sauer’s new .223 Rem 55-grain Elite Ball FMJ. The rounds list an MV of 3,240 feet per second, yielding 1,282 foot-pounds of energy. Previous testing of the Bobcat Upper showed significant degradation of velocity. A 62-grain HPR Black Ops load, factory-rated at 3,021 feet per second, only made 2,192 feet per second from the shorty upper. It delivered only 661 foot-pounds of muzzle energy. That’s about the same as a hot-loaded 10mm from a standard pistol — nowhere near rifle or even carbine ballistics. It is a pistol after all.
I fired the completed pistol first by strapping it with the SB pistol-stabilizing brace. I was easily able to keep the XS sights in view. It delivered well-centered hits to the middle of a B-27 silhouette target at 21 feet.
Next, I tried using the sternum position. Here I found that I was looking over the top of the sights. If I had mounted a taller red-dot optic, I probably could have gotten a decent sight picture.
Extending the pistol out with two hands using the Tactical Link sling in place worked quite well. When locked out, the rear of the pistol brace rests away from (but in front of) the face. So, make sure you are pushing out against it firmly. The “sling lock” also provides a great sight picture.
The cheek-brace position was the quickest to acquire, especially without the sling in place. In this position, the brace is stabilized against the strong-side cheek without making contact with the shoulder. This gave me a quick, perfect sight picture with the XS sights. This configuration offered reasonable control of the gun.
Final Thoughts on Building AR-15 Pistols
The completed pistol experienced no malfunctions throughout the test. Accuracy was more than satisfactory when using the cheek-brace or sling-lock position. Note that video of legal shooting positions and techniques is available at the SB Tactical website.
Keep in mind that ATF regulations seem to change on a regular basis. When I originally started research for these articles, an angled grip mounted on the forend was permissible. By the time I actually began writing, ATF had eliminated it as a permissible feature.
If you are going to own and use a modern pistol of any kind, it is important to keep abreast of ATF updates. In the end, it might be simpler to get the SBR Federal Tax stamp. As an SBR, there is no concern about permissible shooting positions or accouterments … at least for now.
About Scott W. Wagner
Scott W. Wagner is a criminal justice professor and police academy commander from Columbus, Ohio. He has been a police officer since 1980, working as an undercover liquor investigator, undercover narcotics investigator, patrol officer, SWAT team member, sniper and assistant team leader. Scott is currently a patrol sergeant with the Village of Baltimore, Ohio, Police Department. He has been a police firearms instructor since 1986 and is certified to instruct revolver, semi-automatic pistol, shotgun, semi- and fully automatic patrol rifle, and submachine gun.