Sintercore Charging Handle Review: 5.56 Tripwire
VOSB Highlight: Sintercore 5.56 Tripwire Charging Handle Review: We Don’t Need no Latches
Marine, Nerd, Owner of Sintercore
Neal Brace joined the United States Marine Corps Infantry in 2005, eventually joining a Scout Sniper platoon. The role of radio man was eventually foisted upon him because of his known status as a nerd, though he found that the job suited him well. The training that came with the territory only helped reinforce Neal’s love of science, as he learned about satellites, communications, and how technology can act as a force multiplier on the battlefield. His two tours (one in Iraq and one in Afghanistan) were formative experiences for him. Hard work, responsibility, risk, and loss helped Neal grow, and would eventually serve him well through a series of small business ventures.
After leaving the Corps in 2009, Neal meandered, wondering what his first business venture should be. By 2011, he’d decided to get into the training game, and won several contracts training armed security teams, running pistol/carbine/precision rifle courses, and generally shooting a lot. Feeling that training wasn’t enough, Neal’s inner nerd led him to tinker with 3D printing and a number of AR parts designs. He realized that 3D printing was great for prototyping, and could even be used as a means of production. The first project that came to fruition was the 3DX Muzzle Device, which saw plenty of buzz and kind words from the likes of TTAG. You might think that 3D printing is only for plastic, but the 3DX is made of Inconel 625, which is a 100% dense metal that is nearly indistinguishable from a billet piece of aluminum. In fact, Neal’s first foray into parts production caught the attention of Ares Defense. Sintercore was asked to demonstrate the 3DX for the SOCOM Science and Technology Directorate at MacDill Air Force Base in Florida. The reception was positive, but high manufacturing cost (this device could only be 3D printed) was a roadblock for the military. As Neal moved on and tested other parts designs, the Tripwire 556 was born (there’s also a 762 version).
Not Reinventing the Wheel, Just Making it Better
Charging handles are everywhere. It seems as though everyone in the AR parts game has decided that you need to make a charging handle in order to be taken seriously. BCM, Rainier, Fortis, POF, Strike Industries, Aero Precision… the list goes on. Most of these manufacturers make one boastful claim or another. Their charging handles are ambidextrous, gas-busting, modular, aggressively textured, kind, thoughtful, supportive, charming- the list of proposed benefits doesn’t seem to end. In order to break down which charging handles are actually different or more useful than others, we’ll need to investigate the role of the charging handle in the function and manipulation of the rifle. Moving forward, I want to make clear that the industry term for the bit that the operator pulls back on in order to release the charging handle and draw back the bolt is a charging handle latch. Sintercore refers to their “tripwire” lever as a latch on their website, but I’m going to call it a “tripwire” in order to avoid confusion.
What does a charging handle do, and how is the Tripwire different?
Fundamentally, the charging handle is a means of manually drawing the bolt back and cocking the hammer. This action can clear malfunctions, show that the firearm is unloaded/clear, or eject a chambered round. It’s an important part, and although a basic charging handle will do the job just fine, the AR15 has spawned an industry dedicated to innovation and parts of every color, function, and personality. Sintercore is bringing two things to the table: a lightweight piece of hardware, and a truly ambidextrous latchless design. Basically, most charging handles include a latch (usually on the lefthand side) that a shooter must pull back in order to “release” the charging handle and draw the bolt back. Some companies offer larger latches, some offer a latch on both sides. A latchless design simply requires a bit more force (initially) to pull back, and the “tripwire” is designed to hit a piece of the upper receiver cutout and give way when enough force is supplied, releasing the handle and filling the role filled by the latch on other designs. No shooters should have an issue using a latchless design, as the force required to draw is minimal.
It’s important to keep the charging handle in place while firing, because no one likes a metal “T” in the nose (this is a joke, and extremely unlikely, if not nigh impossible even if the charging handle weren’t secured properly- relax, internet). Really, the charging handle should stay in place so that it doesn’t rattle around or potentially impede function. The Tripwire 556 Charing Handle is held secure by friction alone: the spring-loaded “tripwire” holds it tight to the upper receiver. When pulled back, the “tripwire” trips on the upper receiver, releasing the charging handle. It’s a truly ambidextrous design, which simplifies function.
It’s simple, and doesn’t include features to divert escaping gas from suppressed builds or any hyper-aggressive texturing. It’s a simple part that functions as expected, it’s well made, and it’s light. It will definitely scratch your upper a bit, but the AR15 is a rifle, not a Lamborghini. The reason it scratches is that it drags on the upper receiver cutaway. Even coatings like cerakote are just that- coatings- and sit on the surface of the metal. Most charging handles will have this effect, but it may be slower to occur with a latched design because the operater may fully depress the latch before drawing the charging handle, thereby circumventing the “scrape” that occurs with a latchless design. According to Brace, “[I’ve] not personally owned one, but with an OEM handle the latch does the exact same thing. The carbon fiber is much softer than aluminum, and especially aluminum that’s hardcoat anodized. Any time that there’s a paint, it’s not embedded into the aluminum, so it’s an unfortunate byproduct of the process.”
3D Printer Carbon Fiber
Carbon fiber has extremely high strength to weigh ratios. I was curious as to how it can be “3D printed.” According to Neal, the simple answer is that powdered nylon is shot with a laser, which melts the nylon particles together in a matrix. Then, a proprietary graphite mixture is fused into the nylon matrix using a process called laser sintering. Sintercore is named for this process. Have a look at this video for more. The Tripwire’s actual “tripwire” mechanism that releases the charging handle, is made of 3D printed/sintered carbon fiber composites. The minimalist design and carbon fiber latch brings this charging handle to just 1oz. To be fair, your standard, no glitz charging handle weighs about 1.1oz, and the Fortis Hammer weighs 1.50z, so it’s not necessarily going to be a transformative Jenny Craig treatment for your rifle.
Red Hatchet Says…
It’s a totally ambidextrous, latchless, convenient little piece of work. The 3D carbon fiber adds an interesting element, and I wonder how many 3D carbon fiber AR parts we’ll see coming down the pipe. They’re already making carbon fiber wrapped barrels, handguards, and even lower receivers. I’m actually a big fan of the Tripwire 556 over more aggressively textured designs. It’s bulky enough to operate with gloves, and doesn’t chew up bare skin like the Fortis Hammer. There’s a minor convenience element as well: being able to charge the rifle from either side without pulling a latch is actually more useful than I would have initially imagined. It also won’t quit- it’s machined out of bar stock 7075-T6 aluminum, so it’s a tough sonofabitch. Try as I might, I couldn’t rattle it loose at all, so the friction lock works well. Am I convinced that it’s worlds above a $19 standard AR15 charging handle? No. Would I buy it? Well, I bought a Fortis Hammer, so I probably would. The AR15 world is full of parts that aren’t revolutionary, but are definitely cool enough to pick up anyway. After all, it’s pretty slick. At this price range, it’s really down to the BCM Gunfighter or the Tripwire 556.
What’s Next for Sintercore?
Neal’s a tinkerer. He’s constantly revamping his designs, and when he does he offers a free part upgrade to purchasers of previous iterations. First on the agenda is likely a change of material for the “tripwire” device. Farewell to the sintering process, and on to a new discovery that’s just as strong and better in a few ways. He’s also getting back to his Scout Sniper Platoon roots, working on accessories for precision long range rifles. Neal’s also still chasing his dream of creating the perfect muzzle device, but he was somewhat tight lipped about the irons that he’s got in the fire right now. We’re excited to see what comes down the pipe, and will be leaving the Tripwire 556 on our DMR build in the meantime. Neal’s parting words of advice for Veterans who might be starting a small business is to seek out knowledgeable folks who can help them, and to use the discipline and “…find the specialists. You need to take the initiative that you learned in the military and use that to find people who will be able to help you.”