Knife Review: Extrema Ratio RAO II

Extrema Ratio’s RAO II is an update of the original RAO which was developed back in 2006. Designed as a super tough, compact, survival and field knife, the brutish RAO was an immediate modern classic. In 2014, with improved ergonomics and a new drop-point blade, the RAO II widens the appeal of the RAO to those that found the original tanto blade a bit too specialised. On a personal note, this is one of those knives I knew had to be in my life, and it has not disappointed.

The Blade and Handle Geometry:

Most knife specifications have a basic description of the blade geometry, but in this section I will be taking a more detailed look at geometry and balance.

Using a set of gauges and precision measuring equipment including a Vernier protractor, callipers, fixed radius gauges and the unique Arc Master adjustable radius gauge (the one that looks like a crossbow).

These measurements have been tabulated and are presented along with a few reference blades (8″ Chef’s Knife, 5.5″ Santoku and the popular Fällkniven F1).

Key aspects such as the primary bevel angle, grind type, blade depth, blade thickness, length, weight are detailed, along with balance information.

The ‘Balance relative to the front of the handle’ tells you if the knife will feel front heavy, or if the weight is in your hand (a positive value means the weight is forward of the front of the handle). The ‘Balance relative to the centre of the handle’ indicates how close to a ‘neutral balance’ the knife has in the hand.

In the case of full convex grinds the approximate centre of the grind is used for the primary bevel angle estimate.

The blade is made from Böhler N690Co steel.

New for 2018! BESS Certified sharpness testing:

The BESS ‘C’ scale of sharpness, developed by Mike Brubacher (Brubacher Edge Sharpness Scale) will now become part of Tactical Reviews’ knife testing process. Initially this will be used to verify the sharpness of the factory edge and allow the knife to be brought to a minimum standard sharpness before testing a blade’s cutting performance.

The RAO II’s factory edge has an average BESS ‘C’ sharpness of 279. A score below 300 for a factory edge is good and it will slice 80gsm paper nicely and slices into the rounded edge of a doubled over sheet of the same 80gsm paper. Unfortunately a small nick in the original edge catches in some cuts causing some tearing. It is quite common for factory edges to have some flaws, and these can easily be sharpened out, so this is just an observation.

Explained by the Maker:

The reasons for certain design choices may not be clear when simply looking at an object, so this section is intended to give an insight into the thinking behind a design by speaking to the designer themselves.

Unfortunately I can’t always get time with the designer so will use this section to include relevant information about the knife and its designer.

From Extrema Ratio’s product information:
“In June 2006, the “185° Rgt. Ricognizione e Acquisizione Obiettivi” (Target Acquisition Regiment) airborne “FOLGORE” (185° RAO) entrusted to Extrema Ratio the development of a unique knife fitting the unit’s specific operational duties. This resulted in the RAO: not an oversized folder as much as a compact survival & field knife, with a heavy and dependable blade. Its very reliable locking system, assisted by an extra safety device, effectively turns this folder into a fixed blade knife. The opening and closing is to be performed with both hands in order to minimize the risk of self-inflicted injuries, as the blade, because of its weight, is a veritable guillotine. The extra safe device is a steel pin to be hand-screwed through two holes by the guard section of the massive Anticorodal aluminum handle – its presence between blade and hand also acting as a great psychological boon. The sheath is an essential part of this weapon system: it holds a diamond-plate sharpener and enables user to carry the knife either in open position, held in place by a cord and two clips, or closed, inside the front pocket. The sheath can be attached to tactical vests or common belts, being MOLLE system-compliant.

RAO II is the new version of the celebrated Extrema Ratio RAO knife; it comes with a new drop-point blade and an improved handle, rounded at the upper corners for a more ergonomic grip. The extra safety lock effectively turns it into a fixed blade knife enabling great chopping performance with no risk of injury. The sheath can hold the knife in open position for frequent use, or in closed position inside the front pocket. It comes with a diamond-plate sharpener to always keep a perfect edge. ”

A few more details:

Extrema Ratio’s knives are always well presented; the RAO II comes in a quality cardboard box.

Sliding the lid off, shows the RAO II (in a plastic bag) fills the box.

The RAO II arrives in its dual purpose sheath. We need to have a closer look at this sheath before we move onto that amazing knife.

On the back are the MOLLE fitting straps. As supplied they are not woven into the webbing but just held with the press studs.

As with most MOLLE mounts, the fit is pretty tight.

If just using the webbing next to the press studs, the MOLLE straps form a belt loop, which is how I’ll be using this for the most part during testing.

This dual purpose sheath has a large front pocket with plastic buckle fastener holding down the flap.

The flap has another strap attached to it with two press studs. This is the retaining strap for when the sheath is used to carry to opened RAO II.

Releasing the strap from the two press studs and now you can see where the blade of the opened knife is inserted.

Flipping open the flap covering the front pocket and you find the diamond sharpener slipped into a small pocket in front of the main compartment.

This sharpener is a steel plate with a diamond pad on it.

The diamond pad appears to be a special fabric adhesive tape with a diamond abrasive.

There are the three major components, the sheath, the knife, and the sharpener.

‘RAO II’ is engraved on the back-spacer.

There is no mistaking the presence of this knife. Even when folded it is a beast.

Out of the box, the RAO II is actually locked shut. We’ll look at the special locking/safety pin next.

So, one of the RAO II’s special features is its safety locking pin which effectively makes it into a fixed blade knife. This fits through the finger guard and can be fitted with the blade open or folded.

One end of the pin is threaded, so it screws into place.

The pin is on a loop of elastic, so once removed it cannot be dropped or lost (unless the elastic cord is cut).

With the safety pin out of the way, the blade can pass between the two parts of the finger guard.

A sliding bolt-lock is used, and this also acts as the back-spring that keeps the blade in the folded position.

Now the blade is opened, we can put the safety pin back in place to secure the blade in the open position. There is no getting past that pin.

Pivot tension is set using a single sided pivot bolt (the other side is a blank plate). The pivot bolt head has a notched edge which allows it to be securely locked in place using the small screw that fits into one of the twelve notches. With the pivot locking screw in place, the pivot bolt cannot turn at all. You can beat on this knife as hard as you like and that pivot bolt won’t come loose.

The improved ergonomics are obvious with well rounded edges all round the handle. Extrema Ratio’s handle style is recognisable with the first two fingers grip. The RAO II also includes a third and fourth finger grip.

There is jimping at the base of the handle for the thumb, when using a reverse grip.

The H is tight and precise, fit and finish is excellent all over.

And now onto that purposeful blade. A drop-point with bayonet grind, the RAO II’s blade is very deep. The area where the logo is printed is thinned slightly from the full thickness to provide a grip for opening the blade with.

A close look at the blade tip and edge bevel.

The plunge line is well rounded to maximise strength. The slight double-plunge effect here is caused by the primary bevel meeting the blade opening grip and its different radiusing.

With the blade halfway open, you can get a clear view of the locking notch in the tang. The bolt lock drops into this notch when the blade is fully open.

So we’ve taken the folded knife out of the sheath front pocket, opened it and fitted the safety lock pin. Instead of taking the pin out again to fold it, we can simply fit it into the sheath to carry it like a fixed blade. Note one of the press studs is uncovered as the retaining strap now only reaches the top press stud.

A view from the back with the opened knife sheathed.

The retaining strap sits over the deep finger guard, giving it a very secure hold.

What it is like to use?

If you ignore the pivot bolt and bolt lock button, the impression of this knife is not of a folder, but of a chunky fixed utility knife. In a bare hand (I take XL gloves) the finger grips are not quite in the right place. With gloves on they are a better match, but are definitely a better fit for large gloved hands.

It’s big, but somehow seems perfectly reasonable once you pick it up. However, that handle is a significant size and the blade very deep, just look at the next photo.

Putting the RAO II next to a full size fixed blade (using the Extrema Ratio TASK J in this case), its blade is not as long, but it is larger in every other way – and this is a folder!

Extrema Ratio have proven time and again that they put real effort into all the details, including the sheaths. Their sheaths are strong, great quality, and highly functional. For the RAO II, this is taken even further, as the dual function sheath is a carry pouch for the folded knife (plus sharpener) as well as a sheath for the RAO II as a fixed blade.
Due to the dual design, the RAO II does carry high on the belt if used as a fixed blade sheath. This is because there is no hanger for the belt loop which would normally drop the carry height (like it does on most fixed blade sheaths).

The included sharpener, I’d class as one of those emergency options which is great because you have it with you, but not for regular use. I’m glad it is included, but won’t be rushing to use it.

This is a short video taking a look over the RAO II and a technique to make the refitting of the safety lock pin easier.

Video Edited with – Cyberlink Director Suite 5 (PowerDirector 16 and AudioDirector 7)
Camera – Panasonic HC-V770    Microphone – Tonor TN120308BL

Now you’ve seen the video, and the safety lock pin coming in and out, you might come to the same conclusion I have. This is a great feature, and one I use, but there are many times I want to use the RAO II as a large folder and be able to open and close it quickly. In this case the pin is not being used, and if left attached, as it comes with the knife, it then flaps around and hits your hand, the knife and anything else in range. I got sick of this, so decided to alter things slightly and make it easy to remove the pin entirely.

This is my set-up. I’ve taken the original black elastic out of the lanyard hole and added my own loop using 2mm sailing cord.

The original elastic cord with the pin on it is then looped through the sailing cord in a larks head knot.

This larks head knot can easily be loosened and slipped off the sailing cord.

Two overhand knots keep the sailing cord set in the position I wanted.

With this easy modification, that excellent safety lock pin can be set aside for when you want to use the RAO II in more extreme ways, but for general use and really making the most of this knife as a folder, it becomes more of a hindrance. Without that hindrance the RAO II becomes fun to use and revels in its stature and super heavy build.

The bolt lock works so intuitively; as you grasp the knife to fold it, your fingers naturally pull on the bolt as you press the blade into the handle. Unlocking and folding in one motion, as shown in the video.

Talking of super heavy build, this folder is exceptional in the trust you can put in it. That simple idea of the safety lock pin, makes it a folder you can treat just like a fixed blade and not have any concern it might fold on you. Described by Extrema Ratio as a ‘compact’ survival knife, the knife in its sheath is not particularly compact; the dual functions of the carry pouch and fixed blade sheath bulk it up somewhat. The knife on its own however, for the size and strength of knife you get to use, is nicely compact thanks to being a folder.

I’m not going to suggest that this is the most practical knife for general use, but it will make you grin when you bring it out – every time.

Review Summary

The views expressed in this summary table are from the point of view of the reviewer’s personal use. I am not a member of the armed forces and cannot comment on its use beyond a cutting tool or field/hunting knife.

Something that might be a ‘pro’ for one user can be a ‘con’ for another, so the comments are categorised based on my requirements. You should consider all points and if they could be beneficial to you.

_______________________________________________ _______________________________________________
Things I like What doesn’t work so well for me
_______________________________________________ _______________________________________________
Safety lock pin fixes the blade open with complete reliability. If not fitted the safety lock pin flaps around on the elastic cord.
Superb dual function sheath (pouch/fixed blade). Supplied sharpener gets in the way.
MOLLE compatible sheath. Combined pouch / sheath is a little bulky.
Super strong build. Sheath is right-handed only when the blade is open.
Distinctive Extrema Ratio style.
RAO II blade shape more useful to most users.
Basically just awesome.

 

Discussing the Review:

The ideal place to discuss this reviews is on a forum. If you started reading the shorter forum version of the review, but followed the link this full exclusive review, please return to that forum to discuss the review there.
If you read the review entirely on Tactical Reviews, please consider one of the following to join in any discussion.

BladeForums – Knife Reviews (US based Forum for Knife Discussion)

CandlePowerForums – Knife Reviews Section (Largest and Friendliest Flashlight Community Forum)

The BESS Exchange – A forum discussing technical aspects of sharpness and truly understanding your sharpening process.

Knife Review: Extrema Ratio TASK J

Based on the original TASK tactical knife designed by Thilo Schiller, this version of the TASK, the TASK J has been developed as a collaboration with the Jagdkommando Unit, the Austrian Army special forces. Their requirements were for a heavier duty version of the original TASK which could survive more extreme use.

The Blade and Handle Geometry:

Most knife specifications have a basic description of the blade geometry, but in this section I will be taking a more detailed look at geometry and balance.

Using a set of gauges and precision measuring equipment including a Vernier protractor, callipers, fixed radius gauges and the unique Arc Master adjustable radius gauge (the one that looks like a crossbow).

These measurements have been tabulated and are presented along with a few reference blades (8″ Chef’s Knife, 5.5″ Santoku and the popular Fällkniven F1).

Key aspects such as the primary bevel angle, grind type, blade depth, blade thickness, length, weight are detailed, along with balance information.

The ‘Balance relative to the front of the handle’ tells you if the knife will feel front heavy, or if the weight is in your hand (a positive value means the weight is forward of the front of the handle). The ‘Balance relative to the centre of the handle’ indicates how close to a ‘neutral balance’ the knife has in the hand.

In the case of full convex grinds the approximate centre of the grind is used for the primary bevel angle estimate.

The blade is made from ACCIAIO BöHLER N690 (58HRC) steel.

New for 2018! BESS Certified sharpness testing:

The BESS ‘C’ scale of sharpness, developed by Mike Brubacher (Brubacher Edge Sharpness Scale) will now become part of Tactical Reviews’ knife testing process. Initially this will be used to verify the sharpness of the factory edge and allow the knife to be brought to a minimum standard sharpness before testing a blade’s cutting performance.

The TASK J’s factory edge has an average BESS ‘C’ sharpness of 533. Though this officially comes in as a ‘dull’ edge, it will just slice 80gsm paper. Because there are some areas at a BESS ‘C’ score of 407, that allows for a borderline working edge, which is the only reason it is possible to slice 80gsm paper with this factory edge.

Explained by the Maker:

The reasons for certain design choices may not be clear when simply looking at an object, so this section is intended to give an insight into the thinking behind a design by speaking to the designer themselves.

Unfortunately I can’t always get time with the designer so will use this section to include relevant information about the knife and its designer.

Direct quote from Extrema Ratio’s website.
“This tactical knife has been developed together with material experts of Jagdkommando Unit, the Austrian Army special force. It is a multi purpose tactical knife with double guards to avoid accidentally slipping of the hand on the blade. It comes with standard desert side sheath with automatic retention mechanism and protective slap. A fireball flint and striker is placed inside the sheath.”

A few more details:

A well made cardboard box is used for the TASK J.

The full package is wrapped in a plastic bag, and fills the substantial box.

Along with the bagged knife are two leaflets and a quality control card.

Slipping the TASK J out of the bag; the leg strap is kept neatly in place with a rubber band.

Taking a moment here to mention that Extrema Ratio have packed the design of the sheath with so much detail, this needs to be appreciated, so we’ll be covering this before moving onto the knife.

Being a full size knife, there is a removable leg strap to allow you to really keep it under control in vigorous situations.

The leg strap has a double elasticated section so you can fit is snugly without then finding it cuts in uncomfortably.

Both ends of the leg strap are adjustable in length using velcro. There is an elastic cover to slide over the end of the strap end to prevent it from being pulled away during use.

In exactly the same way you adjust the length (by pulling apart the velcro adjustment), you can also remove the strap fully.

For now the leg strap is off and set aside until needed.

Onto the main sheath. The most obvious atypical feature is the full knife handle cover; as shown here, the knife itself is almost fully concealed. This flap is a critical feature to help prevent a knife fitted to a pack becoming a ‘hang up’ hazard. With the flap over the knife handle it is far less likely to catch on something.

Not relying on a fabric to keep the blade from cutting through the sheath, there is a full plastic sheath liner. This is the bottom of the sheath with the special fixing (visible on the front of the sheath) and the black plastic liner plug that closes off the end of the liner, but leaves gaps for drainage.

A high quality plastic snap buckle holds the knife cover flap in place.

Rolling the sheath over and there is a full length MOLLE fixing strap.

The top of that MOLLE strap is what holds the removable knife cover flap in place.

Here the knife cover flap has been folded under the rest of the sheath. Note the thin black cord running down the side of the sheath.

That cord runs all the way down and is held by the MOLLE strap press stud.

Freeing the black cord, and now starting to draw the MOLLE strap out of the loops.

With the MOLLE strap fully released the cover flap can be removed.

Following the thin black cord to the top of the sheath liner.

Give it a tug and a thick fire-steel starts to slide out.

And it just keeps coming… the fire-steel is the full length of the sheath!

The knife retention strap is also adjustable / removable, with velcro holding it in place.

The primary knife retention is not the strap, but is a plastic tab that is part of the sheath liner.

You can see how the side of the handle hits that plastic tab as you insert the knife into the sheath.

Push a little more firmly, and the knife clicks into place. It is now held in the sheath by this plastic tab, requiring a firm pull to free it.

Having covered its feature packed sheath system, here is the TASK J.

Though similar to the TASK in that it has a double-edged, modified wharncliffe blade, the primary bevel is quite different, as well as the blade having a bayonet grind.

The blade is symmetrically ground.

Extrema Ratio’s distinctive Forprene handle is used, in this case the desert colour.

Used on several models, this recognisable handle is particularly effective. The grip design provides a secure dual finger groove and the Forprene material cushions the user from the shock of heavy blows.

Another clear design feature intended for extreme use, is the double guard which provides the greatest protection against the hand slipping forward onto the blade.

A well radiused plunge line keeps maximum strength at the transition from cutting edge to ricasso. Note the lack of a choil which in this case removes the chance of a hang-up if the blade has made a full depth cut.

There is a single bolt to keep the handle in place.

Though an upper guard does get in the way of thumb forward grip, the guard is angled forwards slightly, so you can still take this type of grip with the thumb pushing onto the guard. Note the lanyard /lashing hole in the guard.

A good sized lanyard hole makes it easy to fit a cord if you want, and the tang protrudes from the end of the handle providing a hammering surface.

As mentioned before, the TASK J has a bayonet grind and a military style double edged tip.

Taking a very close look at the tip.

To properly show the proportions of the TASK J, this side shot minimises perspective distortions.

What it is like to use?

Extrema Ratio’s TASK J is not what I would normally think of as your ‘every day’ knife. It is a specifically heavy duty knife, for conditions where you need that absolute assurance the blade is as strong as it could be and will take anything you throw at it.

The superb attention to detail in the sheath design only reinforces how the whole package is intended to work in conditions most of us will thankfully never have to endure. With comprehensive carry options you can pack this knife in all sorts of ways and know it will still be there with you through the worst.

What the TASK J does that is different to most of the other knives capable of demolition/extraction work, is to maintain the more refined feel of a general purpose knife instead of just seeming like a large slab of steel – an important distinction.

Taking the TASK J in hand, and it is a full size knife, having a blade just over 6″ long. The ultra modern looking grip is very comfortable and secure to hold (one reason it features on many of Extrema Ratio’s knives). Despite the amount of meat in the blade it does not feel overly heavy or unbalanced.

In a reverse grip, the top guard does interfere somewhat with the range of movement, and makes it more difficult to bring the blade back close to your arm.

For a thrusting grip, the thumb can sit onto the upper guard thanks to an angled rear surface and this does give the user good power and control.

Going back for a minute to the sheath, the click-retention makes for a very effective system, the knife can come in and out of the sheath repeatedly, yet despite not using the retention strap, it is held securely and won’t fall out. Details like this are not to be underestimated, as working with a knife it is far better to re-sheath it than leave it lying about between cuts, and if you have to move off in a hurry, it stays where it should be and with you. There is nothing flimsy about any aspect of the sheath. Wherever you put it is where it will stay, and it is also fully ambidextrous.

For such a heavy duty blade, the balance is extremely good. It is in front of the first finger, as the balance point sits at the guard itself. This makes it slightly blade heavy, but much less than similar knives, and certainly not fatiguing when using it for finer duties when you want a lighter feel.

Personally I have little need for the double edged tip, and of course this makes penetrating cuts that much more effective.

Extrema Ratio don’t do things by halves, and in this case I’m referring to the blade coating. It is black, properly matt black, without any reflection; only the cutting edge might glint. One consequence of this blade coating is that it does add drag to the blade, which at times can be quite noticeable. When wiping off the blade I particularly find that the blade tends to grip the material and pull it along. I suspect with more use and wearing-in, this coating will smooth out a bit. So for those who don’t need that ultimate stealth anti-reflective effect, this coating can affect the ‘speed’ of this blade. If you like black blades, this is really Black, so you won’t be disappointed.

With there being such a large fire-steel included I was surprised that there wasn’t a striker on the blade spine. Extrema Ratio said that with the fire-steel only likely to be used in very rare instances, if needed, the blade edge would be used. Definitely not something I’d want to do, so I’ll be grinding a small striker into the spine.

Putting the TASK J next to the Extrema Ratio knife that first drew me to the brand, the Fulcrum. The TASK J’s blade is a little wider and shorter than the Fulcrum. With the Fulcrum’s double guard next to the TASK J’s, also note how the TASK J has lanyard / lashing holes in its guard – more flexibility in the way you can use it. It might have been made for the special forces, but this is firmly in the territory of a tough survival /utility knife.

With the TASK being such a good general utility blade, it is no surprise that a special forces unit (the Jagdkommando Unit) were enthusiastic for a heavier version of that blade style, and they certainly got it in the TASK J.

Review Summary

The views expressed in this summary table are from the point of view of the reviewer’s personal use. I am not a member of the armed forces and cannot comment on its use beyond a cutting tool or field/hunting knife.

Something that might be a ‘pro’ for one user can be a ‘con’ for another, so the comments are categorised based on my requirements. You should consider all points and if they could be beneficial to you.

_______________________________________________ _______________________________________________
Things I like What doesn’t work so well for me
_______________________________________________ _______________________________________________
Strong, but well balanced, blade. Blade coating can ‘drag’ when cutting.
Super versatile and effective sheath. Poor factory edge.
Giant fire-steel included. No striker for the fire-steel.
Effective and comfortable grip.
Double guard with lashing points.

 

Discussing the Review:

The ideal place to discuss this reviews is on a forum. If you started reading the shorter forum version of the review, but followed the link this full exclusive review, please return to that forum to discuss the review there.
If you read the review entirely on Tactical Reviews, please consider one of the following to join in any discussion.

BladeForums – Knife Reviews (US based Forum for Knife Discussion)

CandlePowerForums – Knife Reviews Section (Largest and Friendliest Flashlight Community Forum)

The BESS Exchange – A forum discussing technical aspects of sharpness and truly understanding your sharpening process.

Knife Review: Extrema Ratio MAMBA

Extrema Ratio are well known for making knives that are built like a tank; heavy duty fixed blades and folders that will take everything you can throw at them in their stride.
When the new Mamba arrived for testing it was clear this was something quite different; I was struck by how slim this knife is, and by the special sheath with quick release lever locking system – a sheath so slim it is MOLLE compatible because slides directly into the loops of PALS webbing.

The Blade and Handle Geometry:

Most knife specifications have a basic description of the blade geometry, but in this section I will be taking a more detailed look at geometry and balance.

Using a set of gauges and precision measuring equipment including a Vernier protractor, callipers, fixed radius gauges and the unique Arc Master adjustable radius gauge (the one that looks like a crossbow).

These measurements have been tabulated and are presented along with a few reference blades (8″ Chef’s Knife, 5.5″ Santoku and the popular Fällkniven F1).

Key aspects such as the primary bevel angle, grind type, blade depth, blade thickness, length, weight are detailed, along with balance information.

The ‘Balance relative to the front of the handle’ tells you if the knife will feel front heavy, or if the weight is in your hand (a positive value means the weight is forward of the front of the handle). The ‘Balance relative to the centre of the handle’ indicates how close to a ‘neutral balance’ the knife has in the hand.

In the case of full convex grinds the approximate centre of the grind is used for the primary bevel angle estimate.

The blade is made from ACCIAIO BöHLER N690 (58HRC) steel.

A few more details:

The slimmest Extrema Ratio box I’ve come across.

Taking the lid off; this is how the Mamba arrives.

Included is the Mamba and sheath, with a quality control card and a couple of leaflets.

This really is something different from Extrema Ratio. Recognisable in styling, but definitely distinct.

One of the outstanding features of the Mamba is the quick release lever locking system. This is not a new system as it is used in many diving knife sheaths and a few specialist designs, but it is one I’m a real fan of. Easy and quick to use and very secure.

Simply press the lever inwards to release the knife. With the lever pressed in, its wire spring is pushed away from the sheath slightly.

The very unusual sheath has two adjustable plastic clips. They can also be reversed to make the sheath left or right handed. Of course these are used to secure the sheath in place when inserted into PALS webbing.

With the clip removed from the sheath you can see the internal locking lugs. One side is open and has finger tabs to allow you to open it further for adjustment or removal.

All along the sheath are holes for the adjustable clips to lock into. Should you just want a super low profile knife, you can take the clips off and use the sheath like this.

A distinctive design feature of Extrema Ratio knives is the finger grip recess in the Forprene handle.

There is a single bolt holding the Forprene handle in place. The screw is a tight fit, and even when fully loosened does not fall out; you will have to undo it and pry it out to take the handle off the full tang.

The full tang protrudes slightly from the end of the handle giving you a small striking surface.

On the spine, near the handle, the model is printed onto the black MIL-C-13924 burnished blade finish, and next to this is the notch that the locking lever fits into to hold the knife in the sheath.

The spine is flat for its entire length. This is an important detail in the operation of the lever lock.

On the right side of the blade it has ‘Extrema Ratio’ printed onto the black finish.

And on the left “58 HRC” is prominently printed with ” Stainless Cobalt Steel” printed underneath.

As a key design characteristic of the Mamba is that it fits into PALS webbing loops, the sheath is the starting point for this design. With the sheath fitted in PALS webbing, you want quick access to the blade and one-handed operation, both of which make the lever lock an ideal choice.

Taking a close look at the side of the lever that touches the knife, you can see several details. The lever has a pivot pin as well as a second pin to restrict the rotation of the lever. At the left end of the lever is the locking lug that fits into the notch in the blade spine. This lug is showing wear of the black coating where it rubs against the spine. Also showing wear is an area to the right of the lever where it gets pressed into the jimping when releasing the knife. Also note the shaping of the plastic sheath which supports and holds the blade end of the handle closely when the knife is locked in place.

When seen with the deep jimping on the spine, the locking notch doesn’t stand out at all as it is the same size and shape as the rest of the notches in the thumb grip.

Another view of that locking notch.

Though a relatively slim blade, there is a full length fuller cut into the full flat grind.

Having a strong Tanto tip, the edge bevel does widen towards the very tip.

Even in this slim blade there are refinements including a nicely angled plunge line and sharpening choil.

What it is like to use?

For a couple of main reasons, the Mamba has been a bit of a revelation. When I first saw it, I didn’t think all that much of it, but I was wrong, it really works.

The first of those reasons – the quick release lever lock. I’m so pleased to see this in a non-diving knife as it is one of those features I’ve been crying out for in ‘normal’ sheath knives.

A thumb release lever lock is so intuitive and easy to use as you basically free the blade just taking a normal hold on the handle. Your thumb sits onto the lever instead of the jimping and you squeeze to withdraw the blade.

The lever lock does require a slightly different technique when withdrawing or inserting the blade into the sheath. I mentioned this earlier in relation to the full flat spine. You need to keep the spine pressed into the locking lever as you withdraw or insert the blade. If you don’t, the sprung lever pushes the cutting edge into the opposite side of the sheath, both dragging on the blade, and cutting into the plastic. A slight pressure of the blade spine onto the lever and the blade glides in and out easily.

While mentioning ‘gliding’; actually the finish on the blade when new is so matt, it is slightly rough and in certain circumstances, this does actually cause some drag during a cut or when wiping clean. The surface finishing from Extrema Ratio is excellent, and hard wearing, so this ‘feature’ may simply be more noticeable on the finer blade of the Mamba than it is on larger, heavier knives.

There is one major disadvantage with the lever lock design; should you accidentally insert the blade into the sheath the wrong way round, the cutting edge runs directly onto and along the metal locking lever which will seriously damage the cutting edge.

Once in the hand, the Mamba is similar in size to flatware (a table knife) but is clearly something much more serious.

Though it has a slim grip, the finger grip in the handle, combined with the deep jimping under the thumb, give you a really secure hold on the knife.

Of course the main reason for the slim design of the Mamba is so that it, and its sheath, can fit into PALS webbing (so is MOLLE compatible) for ease of integration into your gear. Many people carry a knife in their PALs webbing, but either have a folder clipped onto it, a large knife with MOLLE compatible sheath, or (something that makes me cringe) in some cases an unsheathed knife slipped into the loops.
Here I’ve got it fitted to a MOAB 6 bag, but it works even better on the shoulder strap of a backpack.

Before fitting, take off the clips and try the sheath in the position you are considering, and check your thumb will land on the locking lever. Then refit the clip nearest to the handle and try once more to check it all works. There is a good reason for checking how well it works at this point.

When mounted, the adjustable clips are positioned so that they hold onto one line of webbing. The clips need to be opened on both sides of the sheath to be able to slide, so fitting can be a bit awkward. This is due to the clip near the tip of the sheath having very little room to move as it is pressed against the bag/load carrier on one side. You don’t want to have to do this many times, hence the earlier trial fitting I mentioned.

Although you have to fight with one of the clips to fit the Mamba into PALS webbing, the tapered tip of the sheath slides through the loops very easily.

So, being designed to fit into PALS webbing, compared to the Extrema Ratio ‘standard build’ for a knife, it is quite a bit smaller. To give an idea of this, here it is next to the Extrema Ratio TASK J.

And unsheathed as well.

Initially the Mamba is not a knife I would have been that excited about; a slim knife designed to fit into PALS webbing. Useful maybe, but not that exciting. This is certainly not how I feel about it now after spending time with it.

In many ways, Extrema Ratio got me hooked with this one by using the lever lock. I just hope they introduce this for a few other models, including the larger knives. On top of that is the fact that the more you use knives, the more you realise you don’t need as much knife as you thought you might. So, often people carry around seriously heavy duty tools that are never really put to use. In terms of cutting power, the Mamba is more than capable of most everyday jobs and its slimmer blade (though not weak at 3.8mm thick) makes many cutting jobs easier. It really is a multi-purpose ‘utility blade’, in all the best possible meanings of that term.

If only Extrema Ratio could include a belt loop fitting, perhaps sliding over the sheath like the MOLLE clips do, as I would like to be able to carry the Mamba securely without a load carrier or backpack. Light, slim, easy to work with and an excellent quick release lever lock for sheath retention, I’ll be carrying this whenever I can.

Review Summary

The views expressed in this summary table are from the point of view of the reviewer’s personal use. I am not a member of the armed forces and cannot comment on its use beyond a cutting tool or field/hunting knife.

Something that might be a ‘pro’ for one user can be a ‘con’ for another, so the comments are categorised based on my requirements. You should consider all points and if they could be beneficial to you.

_______________________________________________ _______________________________________________
Things I like What doesn’t work so well for me
_______________________________________________ _______________________________________________
Quick Release Lever Lock used to retain the knife. Can be very difficult to adjust the MOLLE clips when fitted into the PALS webbing.
Slim and Versatile Blade. Handles as easily as flatware. No Belt Loop.
The Sheath fits Directly into PALS webbing loops. Black Blade finish can ‘drag’ when cutting.
Secure Grip provided by the finger groove and heavy jimping. Inserting the blade the wrong way round can blunt the blade.
Ambidextrous.

 

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