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Review of the Zero Tolerance 0550 Tactical Knife


Last month, I wrote an article about the Hinderer XM-24 I picked up.  Fantastic knife – it gave me a real appreciation for custom knife design and execution.  I’d very much like to get a smaller Hinderer knife that would be easier to carry during the work week than the rather large XM-24.  The Hinderer XM-18 fits the bill, but there’s not one to be found at a reasonable price as of this writing (more stock of the XM-18 is expected next month after Blade Show).  Such is the price for wanting a high-demand, low production product – it’s good to be Rick Hinderer.  🙂

Since I couldn’t readily get an XM-18, I started looking around at other options, and decided to give the Hinderer designed Zero Tolerance 0550 a try:

The Zero Tolerance (or ZT for short) 0550 represents a collaboration between ZT and one of the hottest knife makers on the planet – Rick Hinderer.  Collaborations of this nature is something which the ZT brand is well known for doing, and has had several successful past collaborations.  Zero Tolerance first released a limited edition model prior to the ZT 0550 called the 0551.  It was identical to the “regular” production ZT 0550 in nearly every way, except for the blade steel used, and the G10 scale pattern.  My guess is the ZT 0551 was used to gauge interest in the design, and lead to the ZT 0550. Here are the stats on the ZT 0550:

Steel: S35VN
Handle: Textured G-10
Blade Length: 3 1/2 in. (8.8 cm)
Closed Length: 4.625 in. (11.75 cm)
Overall Length: 8.125 in. (20.6 cm)
Weight: 5.8 oz.
Price:  $250.00 MSRP.

The knife is constructed as a titanium frame lock and shares certain aesthetic and functional similarities to Rick Hinderer’s own XM line of custom knives.  The blade length places it most closely similar to the 3.5″ XM-18 – a key reason behind my purchase of the knife.  During the week I wear suits and dress slacks to work.  The 7.8 ounce, 4″ XM-24 I own is just a bit to big and heavy for my work week attire.  Having carried ZT 0550 for a few days, it’s right at about the upper limit of both size and weight I’d personally want to carry during the week.  For size comparison, here’s a photo of the ZT 0550 with my Spyderco Manix 2:

Impressions:  Overall, I think the ZT 0550 is a good looking knife.  The Hinderer influenced blade shape with a stone wash finish applied to both the blade and the titanium knife frame is very pleasing to my eye.  Here’s a photo of the backside of the ZT 0550 – you can also see the blade markings and pocket clip:

My XM-24 has a media tumbled finish applied to both the blade and titanium back side, and I’m torn as to which finish I prefer.  Visually, I like the clean, uniform stone washed finish better.  Functionally, I know the tumbled finish will do a better job of masking regular wear to the finish – a big benefit for an expensive knife you may one day sell on the secondary market. Here’s a photo comparing the two knives from both a finish and size perspective:

The black G10 handle is “grippy” but not overly aggressive as to be abrasive feeling or damaging to clothing.  I’m not crazy about the appearance of the pattern on the G10 scale which is included with the knife.  I was fully prepared to really not like it based on photos I saw of the knife, but when I received the knife, dislike gave way to ambivalence.  I don’t hate it, but neither do I like it.  Fortunately, much like Hinderer’s own XM series of folders, accessory G10 scales can be purchased in a variety of different colors and patterns.  Here’s a photo of my ZT 0550 sporting a brown G10 scale, with a traditional Hinderer pattern:

My favorite Hinderer G10 scale for the ZT 0550 is the blue/black scale:

Looking at more functional considerations, I’ll begin with the knife steel – Crucible’s S35VN.  The knife world has seen the emergence of many “super steels” in the past decade, but none so popular as S30V (due primarily to custom knife maker Chris Reeve and his extensive use of the steel).  S35VN is now Reeve’s primary steel of choice, and other knife makers have quickly followed suit – Rick Hinderer also uses S35VN extensively in his knives.  Compared to S30V, S35VN improves over S30V in several key areas including toughness (more difficult to chip), corrosion resistance, ease of sharpening, and machineability.  This is my second knife made with S35VN and I’ve not used either enough to have had need to sharpen them, so I can’t yet comment on how it performs from use.  It is important to note that the manufacturer’s heat treating of their steel is a key differentiating factor – not all S35VN knives are created equal.  So the buyer should not assume for example that a Zero Tolerance 0550 will perform to the same level as an actual Hinderer XM knife simply because both use S35VN steel – Hinderer’s steel heat treating process is considered to be among the best there is.  I will say though that the ZT 0550 came impressively sharp from the factory.

The pocket clip of the ZT 0550 is the same used on the $30.00 Kershaw Skyline (both Kershaw and Zero Tolerance share the same parent company – Kai USA).  Like the black G10 scale, I’m rather ambivalent about the pocket clip.  True, it’s neither a fancy pocket clip, nor is it a deep carry type  – but it is perfectly acceptable from a functional perspective.  You can debate as to whether a knife at this price point should have the same pocket clip as the $30.00 Kershaw Skyline, but it works well enough for me.  There is however a problem I did note with my ZT 0550…


In most liner lock and frame lock style knives, a simple mechanism is used to retain the blade in the folded position called a detent – a depression in the blade which is engaged by a ball partially embedded or set in the liner or lockbar.  Opening the blade of a frame lock design knife requires the user to exert sufficient force to overcome the spring-like load pushing the ball into the blade detent by the lockbar.  If the retention force created by the detent is too little, the blade can open in your pocket and creates a risk of injury for the user.  Too strong however, and the blade becomes difficult to open.  Striking a happy medium is an interesting challenge for knife makers and in many respects, the amount of detent overcoming force needed on a knife is a matter of personal preference.  By my standards, the detent on the ZT 0550 was excessively strong, and interfered in the reasonable deployment of the blade using the thumb studs.  I could open it via the thumb stud, but it was, shall we say, a pain in the thumb .  I modified my technique by placing the topside of my thumbnail against the thumb stud, and flicking outward for deployment.  Less painful, but still only resulted in about 1 in 3 effective deployments of the blade, without using any wrist motion to aid in deployment.  Not good.

I first assumed that the issue was unique to my knife, and began scouring the Internet for any user feedback on the issue.  As it turns out, among the roughly 15 video reviews, written reviews, and forum posts I found on the topic, the majority of the users (10) reported a negative experience with the detent.  A Kershaw/Zero Tolerance company representative reported that they’d seen approximately 10 ZT 055x knives returned for warranty service due to detent related issues.  He further promised that if I sent the knife in for factory service, he’d personally see to my satisfaction.    A great offer, but I hated to be without a knife I purchased to hold me over until I could purchase a more desirable knife (the Hinderer XM-18) so I explored other options to resolve the issue.


In speaking with other ZT 0550 owners on the issue, I received many suggestions on how to resolve the detent problem I was experiencing.  Some pointed to technique – if care is not taken when opening the knife, pressure can be applied to the lock bar, increasing the drag of the detent ball, and making it feel as though the knife is harder to open than it otherwise would be.  Checking my technique, this was not my issue.  Others suggested disassembling the knife and applying some lubricant to the friction points.  Since I wanted to change out the scale on my ZT 0550, I had the perfect opportunity to do lube the knife up in the process:

I applied liberal amounts of Militec-1 lubricant to the ZT 0550 (which was reasonably simple to both disassemble and reassemble) put it back together, and while the lubricant did help, the detent was still overly strong.  I even attempted to adjust the tension of the pivot screw which also didn’t help.  The final advice I received seems to be the most effective – accelerate the detent wear in process with repeated opening and closing of the knife.  Over time, through normal use  the detent ball will wear a bit of a channel into the blade along its natural arc of travel.  So while watching television, I repeatedly opened and closed the knife – hundreds of times.  This helped substantially – by as much as 50% or so I’d imagine.  Now, this particular solution will only be so effective, and a point of diminishing returns will be reached.  I’m not sure if I’ve hit that point yet or not.  Right now the detent resistance is “bearable” for me – stronger than I think it should be much much improved.  I may still send the knife to Zero Tolerance after I’m able to secure a Hinderer XM-18, and see what improvements they can create.  Time will tell.

This is my first exposure to the Zero Tolerance brand – a relatively new brand in the marketplace which attempts to bridge the gulf between production knives and high-end custom knives.  By all measures, Zero Tolerance  seems to be very successful and has a considerable following.  Now, many may be wondering “is a ZT 0550 as good as an actual Hinderer XM knife at a lower price point?”  In my opinion, it isn’t and I don’t think that’s the objective.  True, for many consumers, the fact that you can secure a ZT 0550 at about half the retail price of a Hinderer made XM-18 will make it the better choice for them.  The fact that Zero Tolerance has the capacity to produce the ZT 0550 at numbers to better satisfy market demand is also a plus.  You can actually find them readily available from dealers at a discount vs. Hinderer XM knives which are typically out of stock from dealers and only available at greatly escalated prices over retail on the secondary markets.  The ZT 0550 is also manufactured in much the same philosophy as Hinderer manufactures his own knives  as over-engineered tools.  I like over-engineered products – one of the main reasons why I wear Rolex watches and drive BMW automobiles.  The ZT 0550, like the Hinderer XM knives features an extra thick blade spine, similar to Hinderer’s own knives, and extra thick titanium backside, and of course Hinderer’s signature lockbar stabilizer mechanism.  But I would stop short of comparing the ZT 0550 to an actual Hinderer knife – the robustness, fit and finish, and over all quality of the Hinderer made knife is simply a step (or two in some cases) above in my opinion.  My Hinderer XM-24 has a blade deployment that’s silky smooth and flies open with little effort for example.  Though to be fair to Zero Tolerance, the detent of the XM line of knives has been criticized by some as been too light.  Again, the level of detent is somewhat a mater of personal preference.

I like the Zero Tolerance 0550 – it has the design, form factor, and features I was looking for in a Tactical Folder. They can be readily found on for a GREAT price:

Zero Tolerance ZT 0550 Hinderer Folder

At this point I’m inclined to think I’ll keep it even after I acquire a Hinderer XM-18 for tasks and situations for which I won’t necessarily want to use a hard to find custom knife.  Again, time will tell.

About John B. Holbrook, II
John B. Holbrook, II is a freelance writer, photographer, and author of, as well as and *All text and images contained in this web site are the original work of the author, John B. Holbrook, II and are copyright protected. Use of any of the information or images without the permission of the author is prohibited.

  1. Nice review sir. I’ve been looking at this knife trying to decide on purchasing it..

  2. Travis Wilson says:

    I as well just purchased a ZT0550 for the same reasons you did. I love the knife but was turned off by the detent and the pocket clip but the most amazing thing happened the day of my purchase….I had been planning on buying one for two weeks. I work for the largest knife showplace in the states so everyday I was pulling one out and getting a feel for it. The day I went to work to get one we had received a few more of them to put out so I opened one up to make sure it was the one I wanted and I was ecstatic about what I found inside..A 2nd Gen ZT0550!! I quickly did some research to find out that the issues I had with it were resolved!! It now has an awesome low-carry pocket clip coupled with the cut-out for the lockbar was reversed and enlarged so the detent issue was no more!! This thing is PERFECT now!! I know it might be too late telling you this now but I love that ZT made the effort to correct these issues based on feedback from people like us. Hope this is good news to you as well and I hope ZT can work something out with you so that you can get your hands on the New and Improved 550. It’s truly amazing now and smooth as silk. Hope this helped and great review by the way.

  3. Travis – I now have a 2nd ZT 0550 which is a second gen. Can’t say that all the problems have been fixed (I’m reading inconsistent reports on the detent issue in 2nd gen models). My 2nd one also had to “wear in” but is now much better.

  4. John is right about the detent issue. I fixed mine by cutting a piece of a paper clip to fit the hole in the blade. I them peened it gnetly until it was flush with the blade. No detent so no excessive force necessary to open. I don’t have the tension on the blade set excessively tight and it still stays closed well in my pocket.

    If one wanted to you could play with the length of the paperclip pin and leave a minuscule detent there for the ball to drop in to.


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