BENCHMADE 9051 SBK AF0 II Knife Review


Testing the Benchmade 9051 Folding Tactical Knife

By Rick Shandley

When it comes to a high-quality knife, our motto is to “Honor The Edge.” It’s good to give a knife the respect it deserves, especially when its a tactical knife like the Benchmade 9051 SBK AFO II. Right out of the box this knife is shaving sharp, and we wouldn’t consider cutting on a cardboard box with it…that’s what box cutters are for.

This particular Benchmade tactical knife is a drop-point folding knife, finished in black on black. It’s capable of serving a variety of applications from a dependable, relatively lightweight backpacking knife, to a  solid hunting knife or very efficient folding sheath knife. However, the 9051 SBK is primarily designed as a tactical knife and was tested at Fort Bliss, Texas by select soldiers at the Army Evaluation Task Force in the 5-1 Brigade Combat Team, 1st Armored Division. We’ll get to their findings a little further in our review.

There is one downside to this knife. It’s the fact that not all US states will permit ownership of  a tactical knife, unless you are active military or law enforcement. It’s best to check the laws of your particular state, province, or country first. Nevertheless, there are plenty of active military men and women who read articles on Fresh Air, and civilians can gain an appreciation for this 9051 Benchmade folder and check into acquiring one for themselves.

The Benchmade 9051 knife worked well even after being frozen in ice.
The Benchmade 9051 knife worked well even after being frozen in ice.

From our point of view, outdoor lifestyles and activities inevitably require a person to carry a cutting tool,  whether it be a chipped-out chunk of obsidian lashed to an elk horn handle, or a state-of-the-art knife like the Benchmade 9051. Our review process put the Benchmade 9051 through some grueling tests to see how it would perform in a variety of extreme situations. We found that the Benchmade 9051 promises to be a stout companion that any outdoor person can own and expect to last a lifetime.

To test the Benchmade knife’s automatic opening mechanism, we put it though an extreme cold temperature test. The 9051 was to be immersed in a small water-filled container and placed in a deep-freezer for 72-hours. Temperatures ranged from 15º to 0º for the three days. Then the knife was busted out of the ice block with the mechanisms still frozen solid.  The 9051 was allowed to thaw for three-minutes on a 90º day before the trigger button was pressed. Even while the metal knife chassis, scales, and operating mechanism were still very cold, the blade swung strongly into position without hesitation. The blade-locking mechanism clicked immediately into place and the knife was fully operational. This 72-hour ice-block test was repeated twice. Both times the Benchmade 9051 opened immediately upon thawing with ambient day temperatures and body heat.

The Benchmade 9051 features a glas breaker built into the handle
The Benchmade 9051 features a pommel (for breaking glass, etc.) built into the handle.

Between the ice-block tests, the knife was submerged in water and frozen again for 36 hours, twice. Then the knife was allowed to thaw and dry in the hot sun. No perceptible blade corrosion or mechanical hesitation was evident. After the battery of freeze tests, a film of lubrication could be seen on the blade. This is to be expected from the  radical temperature changes from cold to hot, and possible metal expansion. Also, keeping a mechanical instrument lubricated is part-and-parcel with maintaining the tool. What is impressive is the unfailing ability of the 9051 SBK auto-assist mechanism to swing the blade into position without hesitation every time.

Our heat test put the Benchmade 9051 in the California desert dirt and sand. It was left out in the heat for days. One would expect the black-on-black finish of the blade and scales to take on a weathering, dulling affect. But the anodized finish was unfazed. Whether the owner is left or right-handed, the knife opening button mechanism and blade-lock safety lever are easy to use. A right-hand person would activate the blade with the right thumb, while a left-handed person uses the left forefinger.

During our tests, the 9051 opened every time without hesitation
During our tests, the 9051 opened every time without hesitation

In addition to the blade the Benchmade 9051 features a pointed butt-cap pommel integrated into the knife casing. This works well for smashing ice blocks or breaking a car window to help extract a trapped person in the event of an emergency. The 9051 can be carried in its heavy-nylon fabric sheath or with the spring-steel clip that can be adjusted to the owner’s preference by way of  four different mounting points on the knife scales.

We found the Benchmade 9051 SBK auto-folder to be super sturdy and reliable. The knife scales, or handles, are machined so the knife is comfortable, and there is plenty of girth to hang onto if you really have to do some serious slicing. Benchmade chose to build this knife blade with 154CM high-carbon stainless steel. There are more exotic stainless steel grades available, but 154CM is great for a blade of this length. And the 154CM stainless steel seems to fit this application very well. When it comes to keeping a fine edge on it, well…that’s the responsibility of the owner. There are lots of modern edge honing tools available such as diamond-coated steels, oil and water stones, and ceramic rods. Also, Benchmade offers knife sharpening at no charge for every registered knife owner.


Testing the U.S. Army conducted on the Benchmade 9051 SBK auto-folder was almost the opposite of cold-environment testing. They tested for hot weather and salt-water corrosion. The soldiers who tested the 9051, all with combat experience, evaluated the knife from their practical application view point.

The Benchmade was the only auto-folder to pass the salt-water corrosion test. And they field tested several. In salt-water the corrosion that builds up will tend to bind the opening mechanism of any folding knife. Auto-folders are that much more vulnerable to rusting up and binding if corrosion and rust builds up in the opening mechanism. They found the 9051 to be  extremely rugged and durable as it performed very well in every condition they could put it through.

The 9051 features a blade lock and a removable clip that can be adjusted to various positions on the handle.
The 9051 features a blade lock and a removable clip that can be adjusted to various positions on the handle.

In the grit, mud, dirt, and grind conditions the soldiers put the 9051 through, it still cleaned up nice. Easy clean up was attributed to the open-design of the blade housing. After bashing the blades during impact tests, they did start to develop slack and get loose. This was considered a normal occurrence after subjecting the knife to extreme impact conditions. However, the blades remained intact during the tests.

Overall, the U.S. Army judged the Benchmade 9051 SBK to have performed so well that SFC Kevin Reagan stated, “We have recommended, and submitted the order for one knife per combat soldier.” The 9051 SBK appears to be a solid tool that not only performs great mechanically, but it lends a small degree of confidence knowing  that it’s ready to go. We like it!

Benchmade 9051 AFO II Specifications

Locking mechanism:       Button Auto with integrated safety

Blade Style & Opener:     Drop-point: Auto Open

Blade Material:                 154CM Stainless Steel (58-61HRC)

Handles and casing:        6061T6 Aluminum, open back-spacer

Carry Clip:                          Steel multi-mount adjustable to four positions

Finish:                                  Black hard anodize

Blade length:                     3.56 inches

Blade thickness:             0.125-inch

Open Length:                   8.51 inches

Closed Length:                4.95 inches

Weight:                              5.8 ounces

Handle thickness:          0.60-inch

Made In:                            U.S.A.

Retail Price:                     $245

4 thoughts on “BENCHMADE 9051 SBK AF0 II Knife Review

  1. I think by “Not all US states will allow ownership of a ‘tactical’ knife” you mean “automatic” or “switchblade” knife. There are many “tactical” knives from Benchmade or others like Emerson and Spyderco that are not of the switchblade type and many people prefer to not have an automatic tactical knife for several reasons.

    Also, there are many ways around laws to obtain automatic opening knives. Benchmade and some other internet dealers will only sell them to active military or police, but pretty much any other place will sell them to anyone where it’s legal to sell such items (California is an obvious no for selling such knives, but you can still own them, just not carry them in public unless the blade is less than two inches). To have them serviced by Benchmade though, you either need a military/police ID or it won’t be returned as is Benchmade’s policy. But the way around that is to have an authorized dealers send it for you.

    Benchmade has been making good autos for a long time and they’re probably the best known auto knife maker in the world. The AFOII is a big improvement over the original AFO and is probably the best auto they have made to date, but there are many other high quality auto knife offerings that many people don’t know about. Pro-Tech Knives is one, and Microtech Knives another.


  2. Hi Alex,

    Thank you for your thoughtful comment. Yes, I used the word “tactical” to blunt the fact that the 9051 is an auto. Those, like yourself, who know knives would see that it’s an auto. The knife itself, auto or not, stands on its own merit. Because this is a more broad outdoor site, I didn’t go too far into the politics of auto’s at a state level, or ownership requirements.

    Thanks again for your take on this. Perhaps we’ll get to review some of the other great auto folders out there over time.

  3. The tactical knives can also be sold to fire/rescue personnel. As a firefighter and proud owner of a Benchmade 9100 auto, I have never owned a more durable and useful knife. Your review is right on mark!

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