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How To Pick a Duty Knife

Every major knife maker, and many specialty and custom knife makers, has some kind of folding knife geared for law enforcement use. Literally, you have the choice of hundreds of pocket-clipped, folding knives. All of them have a matte black finish. Most have marketing names like Police Model, SWAT, Recon, Hostage Rescue, Rangemaster and, of course, Tactical. How do you even start to sort out the best duty knife?

154CM and ATS-34

First, begin with the blade material. Because the entire purpose of a knife is served by the blade, select the best grade of blade material you can afford. Everything else is secondary. Put your money into the blade.

Some blade materials are much better than other materials. The blade is a compromise of many factors, but it is essentially a three-way showdown of hardness versus toughness versus cost. Blade metallurgy is constantly improving. What was exotic 10 years ago is now commonplace.

The best of the widely available blade materials for police use is the hybrid stainless steel, Crucible 154CM, or the virtually identical Hitachi ATS-34. In the ever-elusive chase for the best in hardness, toughness, durability, edge holding, ease of sharpening, corrosion resistance, chip resistance and cost, this is today’s best compromise.

Crucible 154CM is harder and holds its edge better than the common stainless steels with less carbon, and 154CM has more corrosion resistance than the true high carbon steels. The reality is that tough and hard alloys like 145CM and ATS-34 really are better for police use than the softer or more brittle alloys. While more expensive, they are proportionately better. Yes, in rough use, the right $180 knife probably is three times better than a $60 knife. Lots of hard-use knives use 154CM or ATS-34, so your selection of make and lock design is fairly wide.

Other Alloys

In distant second place for police use are the higher carbon versions of stainless steel. These are known by a number of seemingly confusing alloy names: 440C or AUS-10 and 440B or AUS-8. Heads up! If the blade is marked “440” it is almost certainly 440A, a very soft stainless steel. The AUS-6 alloy has a similar metallurgy to 440A. Anything less than 440B or AUS-8 is probably going to dull too fast for even casual police work. Even the 440C and AUS-10 will dull much faster than the harder 154CM and ATS-34. Some of these lesser blade materials actually dull on the first use. Some lesser blade materials actually chip on the first use.

Update! The very latest blade materials to enter the police duty realm are Crucible S30V, S60V and S90V. About 30% more expensive than a knife made of 154CM, if S30V is in your budget, definitely go for it! It is another step up on the hybrid compromise between hardness and toughness. And for the real knife enthusiasts, check out the Crucible Particle Metallurgy (CPM) alloys, which use a manufacturing process resulting in a near perfect grain structure. The 154CM alloy is now available in the CPM line.

59 to 60Rc Hardness

The metallurgy, of course, determines both the hardness and the toughness. A harder blade will hold the edge longer but be more difficult to sharpen. On their Web sites or in their catalogs, all of the knife makers publish the hardness of their blades in terms of a range on the Rockwell C-scale, Rc.

The key here is that the Rockwell C-scale is not linear. A steel that is 57 Rc is a lot softer than a steel with a 58 Rc hardness. The 154CM and ATS-34 blades are in the 59 to 60 Rc range. It is virtually impossible to get a hybrid stainless steel with a hardness over 60 Rc. At the other extreme, a 440A or AUS-6 blade with a hardness of 56 Rc really will dull on the first cut.

Toughness is a much more elusive attribute to measure. It involves the alloying elements like manganese, molybdenum and vanadium, which increase toughness by controlling the grain structure during heat treating. Since the toughness is an inter-related and interdependent aspect of the finished and heat treated blade, just pick the right alloy, and police-spec toughness will be included.

Tang Lock, Frame Lock

Second, after the blade material, consider the lock design. The internal tang lock, or frame lock, designs are mechanically the strongest and also the least likely to accidentally close during rough use. These designs have names such as AXIS™ Lock (Benchmade), Ultra-Lock® (Cold Steel), Ball Bearing Lock™ (Spyderco) and Arc-Lock™ (SOG), etc.

After carefully checking out the internal tang lock designs, next consider the frame lock designs. The frame lock is different than a liner lock! With the frame lock, the side of the handle or frame slides behind the blade to hold it open. The tightening grip of your hand actually holds the frame lock in place. Next down the list, consider the lock back design. This is stronger than the liner lock, but it can still be accidentally unlocked by palm or finger pressure on the handle back.

At the bottom of the list in terms of strength—and also the easiest to accidentally close—are the liner lock designs. On this design, a strip of metal from the handle liner springs under the blade to hold it open. Because this is the least expensive way to make a knife, these knives are far and away the most popular, accounting for more than half of all tactical blades. Heads up! As the handle is twisted in your hand, it is possible for your finger to engage the liner and unlock the knife.

Some knife makers (Gerber) have seen the double-edged sword that is the liner lock and have added a secondary lock that slides into place. This excellent, easy-to-engage feature prevents the liner from slipping away from the back of the blade tang. Other knife makers (Camillus) use a folded-over edge on the part where the liner engages the tang, which greatly strengthens the liner lock.

The lock design is controversial. To be sure, perfectly acceptable duty knives from outstanding knife makers use a liner-lock design…but look at the internal tang-lock knives first.

One-handed Opening Under Stress

Third, pick a knife that you can open easily with one hand. Your other hand may be busy saving your life. Here is the drill, courtesy of police knife instructor George T. Williams. Start off with the knife clipped in the correct pocket, i.e., left pocket for right-handers and right pocket for left-handers. Grab your own belt with your gun hand. Have your partner grab you by the shoulders or collar and start to shake the daylights out of you. During this, draw the knife and open it to the fully locked position with your non-gun hand.

THAT little exercise will eliminate a lot of knives from consideration for police use! It will also eliminate knives that do not have ambidextrous pocket clip mounting options and opening options. This drill will also affect the tip-up versus tip-down pocket clipped carry position. Whether the knife uses a thumb stud, thumb hole, thumb disk, pocket Wave™ (Emerson) or any of the “assisted” or automatic knives, you simply must be able to open the knife with one hand, period.

Frankly, the police emergency goal of reliable, one-hand opening might lead you to one of the spring and cam levered, assisted-opening knives. In states where it is legal for law enforcement officers, it may also lead you to an automatic knife. It will certainly lead you to a knife that fits the shape of your hand and the length and dexterity of your fingers. It will also lead you to a knife that opens smoothly all the way and one that fully locks every time.

Handle Material and Texture

With just the blade material, lock design and ease of opening, you may find the number of suitable police knives has dropped from a couple hundred options to just a dozen or so options. Consider these tiebreaking features.

The grip or handles may be made from aluminum, titanium or a fiberglass-reinforced nylon. Each is in a different cost category. Regardless of handle material, consider a few things. First, how much weight do you want in your pocket? Titanium is almost twice the weight of aluminum, and even aluminum is much heavier than nylon. Second, think about how easy it is to clean the handle material, i.e., decontaminate it. You may need to clean blood and other possibly dangerous fluids from the knife.

Another issue is grip texture. Your hands will be wet from sweat, blood, water, oil, antifreeze, alcohol, jail gooh or whatever. The surface should be textured enough for a good grip under slippery conditions. In this same regard, slightly exaggerated finger grooves, especially for the index finger, greatly add to the ability to grip the knife. Relief grooves machined or molded into the handles serve exactly the same purpose.

Long and Thick Blade

Blade thickness makes a difference. The police blade should be at least 0.125 inches thick. Sporting-oriented blades will often be thinner, but as the blade gets thinner, it definitely gets weaker. Keep track of exactly how you use your knife. You may find that you use it more like a sharpened crow bar than a surgical instrument. If you use it less for cutting, and more for everything else, you should consider a 0.148-inch-thick blade or even one 0.156 inches thick.

The blade should be between 3.5 inches and 4 inches long, and most knives in the “police” or “tactical” are in this range. Of course, the folder should have a pocket clip. It should allow ambidextrous carry. The best ones also allow the officer to change from a tip-up carry to a tip-down carry, and vice versa. The availability of a training knife, one with a non-cutting blade but with the same feel as the duty knife is a definite plus when it comes to training.

The shape of the knife’s point is almost, but not quite, a personal preference. The Tanto Point was all the rage 15 years ago when tactical folders first took off. What a cool looking point! The problem came when actually using the Tanto Point for the things most cops use a knife to do. Many of us find the strong but thick Tanto Point is just too thick for where we need to get the blade tip. The reality is that the Drop Point, Clip Point or even Spear Point, are all (probably) better choices.

Partial Serrated Blade

Serration is a topic that makes some purist and elitist custom knife makers gnash their teeth. Their “perfect” knife definitely does not have blade serrations, but law enforcement seldom involves a perfect setting. Without question, the serrations cut difficult and coarse materials better than a straight blade. It is as simple as that. Clearly, the police folder should be partially serrated.

Along with hardness and toughness, cost is a part of the three-way knife compromise. So what should you expect to pay for a good tactical folder? The first recommendation, i.e., the use of 154CM or ATS-34 blade material, instantly puts you in the $100 to $150 price range. The good news is that you can also get virtually everything else in that same price range: 3.8-inch-long, 0.125-inch-thick, partially serrated ATS-34 blade, tang-lock, glass-filled grips with ambidextrous pocket clip.

Knives in the $150 to $225 range may add more features and are worth a look. Prices beyond that are more geared to tactical knife enthusiasts who simply want S30V blades and titanium handles, rather than to patrol cops and SWAT operators who probably don’t actually need them or can’t afford them. Knives in the $50 to $100 range are marketed to the police and have some police features, but very few have the both hard and tough, rough-use blade material.

Still looking for a tiebreaker? Clip the knife in your pocket, and then put your hand all the way into that pocket a dozen times. Have you lacerated your hand all the way down to the bone on the knife? In police work, we call that a clue. You are going to carry the knife a lot more than actually use it. Get one that is comfortable to live the rest of your life with until the time comes when you need it.

Published in Tactical Response, Sep/Oct 2006

Rating : 9.2

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