Ontario 6141 MK 3 Navy Knife (Black), stainless steel

This is a terrific knife. Many others have written of the virtues of this knife, so I won't be redundant. I can't believe I hadn't discovered this knife before. It is a nearly perfect military issue in features, form and function. The knife is great, but the sheath has pros and cons. Other reviews have mentioned the matter of the sheath requiring significant effort to insert and withdraw the blade as well as the spring blade retention significantly scraping the coating on the sides of the blade a little more each time the blade goes in and comes out. The retention springs inside the sheath hold the blade very firmly causing scrapes along both flat sides of the blade from about midway down the blade to the tip. I take it the sheath was designed and constructed for very secure retention. If it is desired to keep the blade from having the coating removed along the sides of the blade don't use the sheath that comes with the knife. If that doesn't matter, the sheath is very solid. One reviewer says the knife becomes easier to slide in and out of the sheath with repeated use. The sheath has a one inch wide nylon strap that serves as a belt attachment. There is a wire clip at the top of the strap intended to attach it to a military web belt. Just below the top is the retaining strap with a snap to secure around the knife handle. The strap has a loop so up to a 2 1/2 inch belt may be slid through it. The sheath is perfectly functional and well made if you don't mind the damage to the blade coating by using it.I like the knife and that's why I give it five stars. The sheath is an accessory, and it's up to the owner to decide whether to use it.Update: after scraping up half the blade using the factory sheath, I decided not to do that any more. Using a "Scotch Brite" scour pad I rubbed out the scrape marks and made both sides of the blade look the same. It removed very little of the black oxide coating. Now the blade looks almost new. I work with Kydex, so now the knife has a new sheath and a new look.

If you are looking for a rugged survival knife or are into collecting military knives add this one to your collection. The knife is not as sharp as it could be out of the box, but, two thoughts here: first, for the price I can sharpen it myself; second, if you can't stone a blade, don't play with them. It is an original copy of the USN Mk 3 Mod 0, same with the sheath. The blade is 6 inches from the hilt to the tip and has a black most likely phosphate finish similar to post ww2 small arms finishes. The handle is of a hard plastic with a rubbery grip, typical military. The sheath with it's retaining clips fits the knife snug and will retain the knife until you are ready to deploy the blade. From visual inspection, I can not say if this is a full tang knife, the pommel is a not magnetic alloy along with the hilt but are both meaty. The blade is attracted to a magnet, but from my experience a lot of stainless is magnetic. Overall, this is a good knife at a great price.

Please see reviews of this knife on You Tube. I did so before buying. This "unboxing" review will attempt to discuss things not mentioned in most Y/T reviews. Lowest price when bought was on amazon, but do shop around!Bought "on spec" and likely never used.Scabbard: Marked MK 3 MOD 0 over USN. Simple and sturdy black (paintable) plastic scabbard with single snapped strap for upper part of knife's handle, and cotton cloth "shoelace" leg tie-down. Massive drain hole in bottom of scabbard. Scabbard has typical USGI M-1910 "hook" for attaching to matching GI Pistol belt, or MOLLE users can use a MOLLE ALICE adaptor, or a MOLLE K-BAR adaptor, to attach the scabbard to a PALS platform. Black nylon hanger has a 2-1/4" wide belt loop which >>might<< fit over most GI pistol belts; likely a tight fit to install.The throat of the plastic scabbard has an internal metal collar which serves to secure the knife. This metal collar must be oiled lest it rust. The problem with the collar is that it completely surrounds the blade, and some reviewers have reported that the metal collar may be responsible for unanticipated wear on the edge of the blade. Looking carefully inside the throat of the scabbard, I can see how the knife's edge contacting the metal throat of the scabbard could cause problems. It "may" be possible to use a tool to press in on the locking mechanism of the scabbard's metal throat device and remove it, albeit at the cost of secondary retention. I have not tried this. I think if I was going to use this knife on a regular basis, I might consider one of Spec-Op's very fine nylon scabbards, or make my own Kydex scabbard. YMMV.Blade: Unlike earlier versions of this knife, this knife does NOT have an upswept tip to the knife; the "false edge" goes straight down to the cutting edge of the blade. I prefer this style of blade, as it makes the very tip of the blade stronger and having the tip of the blade "in line" with the central axis of the blade makes many tasks easier than having an off-set, upswept tip.Finish on the blade is some sort of blackened coating. Not "Parkerizing" AFAIK. Given "magnetic" nature of the blade, strongly suggest oiling the blade to deter rust.Blade is strongly magnetic, while guard and pommel are mildly magnetic. This makes me question whether the blade is actually of stainless steel, although advertised as such. Blade and guard are electrically connected; Blade/guard assy is NOT electrically connected to the pommel, which has a 3/16" chamfered hole for a lanyard, which is an included cotton shoe-lace item, and too short to be useful. Users wanting to make a useful lanyard will probably need to use appropriate diameter GI accessory cord in lieu of too-thick GI 550 cord. Blade is marked MK 3 over MOD 0 on one side, and 2V376 on the other side. Saw in back of blade is of "push" type, and given the prominent guard, this should not pose undue risk to the user. FWIW, I prefer "Pull" type blade saws, for safety's sake. There is a straight section of the spine of the blade between the saw and the semi-sharpened "false edge" of the blade which should be useful for ferro rood use. Sharpened edge of blade was "adequate" on my example. Would be possible to greatly improve the edge with some fine stone honing and stropping.Handle: Hard plastic; seemingly harder than the usual OCK Kraton. Marked "USN" within inset circles on both sides of handle. Handle has diamond pattern grips except for 5/16" along molded seams. Some of the mold marks on the seams can be remediated/smoothed, but that's a minor thing. There is a black metal screw going through the plastic handle and secured by a molded-in brass fitting which is NOT electrically connected to the Blade/guard assy, but which IS electrically connected to the pommel. This seems to indicate that the blade tang is not connected to the pommel. I suspect the blade's tang is over molded by the hand grip, and the pommel is secured to the hard plastic grip by the aforementioned screw. The screw is very hard to remove (suspect Loc-tite), and I'm not willing to damage the screw. The strength of the plastic grip and the screw securing the pommel to the grip will determine how much hammering the flat pommel will take.General impressions: Very useful utility/general purpose knife. Reasonable price. Definitely not a chopper. Scabbard should be replaced with a better one. There is enough distance between the guard and edge of blade (choil) for user to "choke-up" on the blade for fine tasks. Blade's point being on central axis of blade/handle makes this knife useful as a general purpose/bushcrafting knife. Careful sharpening should yield substantial improvements.Submitted for consideration.

This is a heavy duty knife. Ontario Knife Company has ceased operations, so these will become hard to find in short order. This is the knife that has been issued to US Navy divers. It holds up fine in and out of the water.Dry it off and oil it before storing it.

This Mk3 has to be one of the very best knives I have ever been issued and carried while serving in the military. This knife is a full tang knife which has been tested by torturing, grueling and putting this knife through every imaginable scenario that those in the NSWF community could come up with! Which is why this knife was selected by the NSWF community chose this knife for their combat knife. As a River Rat, I had the upmost pleasure serving with the best of the best of the Navy's finest. And as a member of the River Rats, I had been issued one of these knives as well. I can say that I would trust this knife with my life, as I believe that the quality of this knife is one of the finest made knives I have come across!