“I could not be more pleased with the finished build.”
An intricately detailed skull is CNC-machined into the Jack10 lower’s magazine well, providing a touch of style and slick reloads under stress. Also note the large integral triggerguard.
The author outfitted his rifle with a 16-inch, Hanson-profile Premium barrel from Ballistic Advantage.
WMD Guns’ lower parts kits come with nickel-boron-coated triggers, disconnects and hammers for smooth pulls and reliable shooting in virtually any condition.
Note the nickel-boron-coated bolt carrier group from WMD Guns.
The author used Geissele’s Reaction Rod to hold all of the upper assembly components, including the barrel and handguard, in place for easy installation.
The S&J Customs Titan compensator helped reduce recoil.
The author chose an Ergo grip because of its ergonomic shape, subtle finger grooves and non-slip rubber construction.
For easy manipulations and added durability, the author installed one of Bravo Company’s tank-tough Gunfighter charging handles with a medium-sized latch.
The Ergo F93 Pro stock and 15-inch SLR Rifleworks 308H Helix KeyMod handguard make the Jack10 rifle infinitely modular to meet a variety of needs.
Let me start by saying that although I built this Sharps Bros. rifle purposely for a review, it was destined to be a keeper. Therefore, all of the components were carefully chosen for their quality and utility. Additionally, I wanted to make sure they enhanced the badass appearance of the Jack10 upper and lower receivers.
Sharps Bros. has become well known in the AR world for its otherworldly lower receivers. CNC-machined from billets of 7075-T6 aluminum, Sharps Bros.’ lowers have magazine wells that look like warthogs, fighter planes and, in the case of the Jack series, skulls. While the company started with 5.56mm NATO AR lowers, it has expanded to include AK-47 receivers and even .308 Winchester/7.62mm NATO AR receiver sets. Which brings us to the heart of this build—the Jack10.
- RELATED STORY: Gun Test – Sharps Bros’ .458 SOCOM Rifle
The Sharps Bros. Jack10 kit features billet-crafted upper and lower receivers. The heavily flared magazine well looks like a skull with some awesome-looking details. Another nice addition is the integral, oversized triggerguard. The flattop upper is streamlined and angular like other billet-crafted receivers. Both of these parts are tank tough and, all together, weigh about 25 ounces. Now came the fun part of building the gun.
The barrel makes or breaks a rifle. If there is one area of a rifle not to skimp on, it’s the barrel. Looking to keep the build somewhat compact, I chose a 16-inch, Hanson-profile Premium series barrel from Ballistic Advantage. In addition to selling direct to enthusiasts, Ballistic Advantage is an OEM provider to many top rifle manufacturers. The company’s Premium barrels are made from 416R stainless steel and feature 11-degree, recessed target crowns. The Hanson profile eliminates all right-angle cuts to increase rigidity and strength without adding lots of additional weight. Each Hanson-profile barrels also comes with a low-profile gas block secured by a roll pin as well as dual Allen bolts. In other words, once installed, this gas block won’t budge. All Ballistic Advantage barrels are high-pressure (HP) and magnetic-particle (MP) tested and are backed by a sub-MOA guarantee.
I capped the barrel with an S&J Customs .308 Titan compensator. Available in black-oxided carbon steel or stainless steel, the Titan features eight exhaust ports designed to trap expanding gases in the baffles and increases dwell time for maximum efficiency. It is a very solid and well-machined device. S&J’s 5.56mm NATO compensator has a reputation for being one of the best on the market, so I expected comparable results from the company’s larger
.308 Winchester version.
Beyond The Barrel
One of the most visual parts of a build is the handguard. Partial to the see-through aesthetic, I mounted a 15-inch 308H Helix KeyMod handguard from SLR Rifleworks. Its framework design is not only distinct and attractive, but lightweight as well. It weighs a scant 8.1 ounces. An interesting design feature is that only the rearward and forward portions of the top of the handguard are fitted with Picatinny rails. In addition to its visual appeal, this also reduces weight. I never use the middle portion on full-length rails, so it certainly won’t be missed. Made from 6061-T6 aluminum, the handguard includes a barrel nut that does not require timing and Grade 8 fasteners. The Helix is a free-floating, anti-rotational and anti-slip design finished with mil-spec hardcoat anodizing. SLR also offers an M-LOK version to those who desire that accessory-mounting platform.
The bolt carrier group that I chose is from WMD Guns. WMD’s claim to fame is its NiB-X coating. The company’s nickel-boron finish allows carbon and other fouling to be wiped off with a cloth. Yes, it’s that easy. Another advantage of WMD’s NiB-X is that it is permanently lubricious, which dramatically reduces the need for additional lubrication. Your gun will run more reliably and for longer periods of time.
Once you clean a WMD Guns bolt carrier group, you will want to switch out the bolt carrier groups on all of your other rifles, which is exactly what I did.
I also installed WMD’s lower parts. The kit comes complete with all of the lower parts except the pistol grip; the trigger, disconnect and hammer are all NiB-X coated. Again, this finish minimizes friction and wear and reduces the need for lubrication and cleaning. The nickel-boron coating’s inherent lubricity greatly smoothens out the trigger pull as well.
For a buttstock, I added an Ergo F93 Pro and attached it to the Sharps Bros. lower receiver. The F93’s eight length-of-pull positions make it highly adjustable, and when fully extended, it offers one of the longest length of pulls on the market. The stock is built around an incorporated carbine-length buffer tube and includes a standard castle nut as well as an ambidextrous sling plate. The cheekpiece remains fixed for a constant and repeatable cheekweld in any position. I especially like that the F93 feels as sturdy as a fixed stock.
- RELATED STORY: 10 ‘Upper Class’ Lower Receivers For Your Rifle
The pistol grip that I installed is also from Ergo Grips. It’s the company’s flagship product and one my favorite grips because of its comfortable shape, subtle finger grooves and easy-to-grip, non-slip rubber construction.
The buffer and buffer spring are from Slash’s Heavy Buffers. Weighing in at 8.5 ounces—about 3 ounces heavier than others on the market—the XH Rifle buffer is constructed of 303 stainless steel and has a sliding tungsten anti-bounce counterweight. The primary benefit of the buffer’s heavier-than-standard weight is that it reduces felt recoil. With a suppressed rifle, it also helps mitigate the effects of overpressure.
Finally, I chose a Bravo Company Manufacturing (BCM) Gunfighter charging handle because I find that its extended handle size makes the task of charging the rifle much easier. I have installed these charging handles on all of my rifles. Available with small, medium and large handles, I favor the medium version because it adds a larger gripping surface, but its not so large that it gets tangled up in other gear that I am wearing.
Sharps Bros. Jack10 Assembly
I assembled the upper using Geissele Automatics’ AR-10/SR-25 Reaction Rod. With the rod mounted in a vise, either horizontally or vertically, the upper receiver can easily slide over the rod. The rod’s integral splines enter the barrel extension and secure the barrel extension from turning. Also available in a 5.56mm NATO version, the Reaction Rod makes the installation of barrel nuts, gas blocks, handguards and muzzle devices easy, and it eliminates torqued receivers, distorted index pins or damaged finishes, all of which can be caused by using some of the receiver blocks common today.
For the lower receiver assembly, I used a Brownells 308 AR Lower Receiver Vise Block to lock the receiver in place. Installing the components is much easier with the receiver held in place with the block. Made from Delrin polymer, this device will not mar or scratch the receiver’s finish.
I could not be more pleased with the finished build. The rifle functions flawlessly and achieved a best group of 0.6 inches at 100 yards with Black Hills ammunition. The S&J Customs Titan brake did its job reducing felt recoil, and I have to admit that the Sharps Bros. Jack10 rifle certainly turns heads at the range!
Caliber: 7.62mm NATO
Barrel: 16 inches
OA Length: 34-37 inches
Weight: 8 pounds (empty)
Stock: Ergo F93
Sights: Flip-up front and rear
Action: Direct impingement semi-auto
Finish: Matte black
For More Information
Slash’s Heavy Buffers
This article was originally published in ‘Gun Buyer’s Guide’ 2017. To order a copy, visit outdoorgroupstore.com.
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