Story and Photos by Michael Janich
One of the major differences between modern self-defense and traditional armed combat is the fact that today’s weapons tend to be smaller and more convenient to carry. Modern laws and social customs also emphasize non-threatening concealed carry over the open display of weapons.
For those who carry knives as part of their personal-defense kit, this typically means we opt for folders instead of fixed blades. And while a well-made, properly designed folding knife can certainly be a potent defensive weapon, it has one major disadvantage: it’s significantly slower to get into action than drawing a knife from a sheath.
As such, serious students of self-defense owe it to themselves to understand, practice, and master the skill of drawing and opening a folder, quickly and reliably, under stress. This skill is a key component of my system of Martial Blade Concepts (MBC) and my students and I spend a lot of our training time practicing “earning” our draws under stress.
I have carried a folding knife as a primary defensive weapon for over 40 years. My first defensive folder was a Gerber Folding Sportsman II back lock with an aftermarket “Flicket” attachment, that allowed the blade to be opened with one hand.
As folding knife design evolved, purpose-designed one-hand opening “purchases” like blade holes, thumb studs, disks, and flippers became the norm. Although all of these work well, they require a specific grip on the knife and a significant amount of fine motor skill. Emerson Openers certainly simplify the deployment process, but they are not available on many folders or the matching training knives that are necessary for serious skill training.
After decades of pressure testing every possible method of opening a folder one handed, the best balance of speed and reliability I’ve found is the inertial opening.
Rather than manually applying pressure to a purchase on the blade to rotate it open, the inertial opening relies on accelerating the closed knife around the axis of the pivot pin, stopping the rotation of the handle, and letting the inertia imparted to the blade carry it into the open position.
Since you don’t have to take the time to find the thumb purchase and never have to actually touch the blade, this style of opening—when done properly—is significantly faster than conventional methods.
There are several different inertial opening techniques, but the key to doing any of them reliably is understanding that the blade always pivots on its pivot pin. The closer the pivot pin is to the axis of rotation of the closed knife, the more efficiently inertia is applied to the blade and the more reliably it opens. For this reason, any whipping motion that centers around the wrist, elbow, shoulder—or any other axis away from the blade pivot—won’t work as well, if at all.
It’s also important to understand that the ability to open a folder inertially is also dependent upon its lock mechanism, the strength of the detent that keeps the blade closed and the blade’s mass.
For example, back locks apply a lot of spring force on a closed blade and do it directly in line with the plane of that blade. Their strong “self-close” function therefore makes opening them inertially more challenging.
Conversely, LinerLocks, Axis-Locks, Ball Bearing Locks and other mechanisms with relatively light detents, lend themselves well to inertial openings. Similarly, saber ground blades with significant heft open more readily than full-flat-ground or deeply-hollow ground blades, because more mass means more inertia.
My favorite inertial opening method starts by gripping the knife’s handle between your fingertips and thumb, so the blade’s pivot pin is roughly even with the top edge of your index finger. Your extended fingers must be perpendicular to the handle of the knife and there should be a space between the handle and the palm of your hand. This grip allows you to rotate the knife quickly and around the proper axis—the pivot pin.
Bend your elbow about 90-degrees and, rotating at the shoulder joint, raise your elbow to the side. Imagine an axis passing through your shoulder and the pivot pin of the knife, so when you raise your elbow, the knife rotates around that pivot pin.
Do this slowly a few times and focus on keeping the pivot pin’s location at a consistent point in space. If you’ve ever been to a wedding reception and had to do the “chicken dance,” you’ve probably got a big head start on this technique.
Once you get a feel for the mechanics of the movement and are able to keep the pivot pin of your knife consistently at the center of your axis of rotation, increase your speed. The goal is to make the rotation as quick and explosive as possible, without letting your form come apart and allowing the axis of the rotation to move.
For best results, start with a knife that has a relatively heavy blade and a light detent mechanism keeping it closed. LinerLocks, Axis-Locks, and similar mechanisms work well for this.
At first, you may hear a slight “clicking” noise—especially with Axis-Locks or Ball Bearing Locks. That’s good, as it’s the blade starting to open, and then snapping back shut. With LinerLocks, the blade may overcome the detent and open a few degrees, but not all the way. No worries. Either way, you’re making progress.
Once you get it right, the blade will snap open fully and lock. After a few successful openings like that, you’ll develop a good “feel” for the technique and will be able to get your blade to open consistently. When you’re ready, try it with lighter blades and other lock mechanisms that have more substantial spring tension. Over time, you should be able to do it with most—but not all—folders.
Once you’re confident in the basic mechanics of the inertial opening, the next step is to refine your technique and integrate it with your drawstroke.
Start by drawing your knife and achieving the necessary grip right from the draw. Then, execute the opening. As you get better, smooth out the motions, eliminate the pauses, and refine your opening technique to make it less exaggerated.
Ultimately, strive to open your knife fluidly, closer to your body, and in a way that doesn’t cause undue wear on your knife’s components over time.
To be honest, inertial openings do cause more mechanical stress on your knife—especially in the case of back locks, where the lock’s mating parts impact each other directly as the blade snaps open.
I once taught this technique to a very strong Air Marshal who carried an old-school Spyderco Police™ Model, that I had modified for him to carry tip-up (this was before this model had a four-position clip). He was so thrilled when he “got” the technique that he couldn’t stop practicing.
Three days after he learned it, he came back to me complaining that his knife’s blade wouldn’t stay locked. He had beaten the mating faces of the blade and lock bar so badly the lock would no longer stay engaged.
Similarly, I’ve had the stop pins of some relatively expensive, highly respected production LinerLocks develop flat spots after a few hundred inertial openings. These flat spots allowed the blade to open further and ultimately caused vertical play in the open position.
Rotating the stop pin to a new contact point solved the problem—for a while. Replacing the stop pin with hardened drill rod solved it permanently but didn’t restore my faith in that brand enough to want to continue carrying it.
At the other extreme, my first Spyderco Yojimbo™ 2—a Compression Lock®—is still going strong after almost nine years and well over 100,000 inertial openings, from the time I first put it in my pocket. Its hardened stop pin shows no signs of peening or flattening, and it still locks up solid.
As a final note, if you’re wondering if inertial openings make your knife an illegal “gravity” knife, consider it this way: If the mechanism of a knife is so weak that anyone—regardless of skill—can inertially open it without practice or special skills, that knife is functionally a gravity knife.
If, however, you can open it, but the average person can’t, you’ve got the edge. K&G
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Martial Blade Conceptswww.MartialBladeConcepts.com
Nine-year veteran of the U.S. Army Intelligence and Security Command, Michael Janich also served a 3-year tour at the National Security Agency. Highly decorated, Michael is a two-time graduate of the Defense Language Institute and served around the world in intelligence and investigative capacities for many years. Utilizing his extensive training in various martial arts and military/LE combatives, he established Paladin Press’ Video Production Department in 1994, running all aspects of video production for 10 years – personally recruiting some of Paladin’s most popular authors and being selected to work with the late Col. Rex Applegate as the producer of his landmark instructional videos on handgun point shooting. Published book and magazine author, Michael has been featured on various television programs and designed knives for many different knife companies throughout the industry. Michael is the founder and lead instructor of his signature knife defense program, Martial Blade Concepts.
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