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USN Mk3 MOD O General Purpose Knife

Discussion in 'Non-Firearm Weapons' started by rcmodel, Nov 15, 2012.

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  1. rcmodel

    rcmodel Member in memoriam

    Sep 17, 2007
    Eastern KS
    Made by Ontario.
    6" Blade with saw-tooth spine.

    Often described and sold as a “Vietnam Combat Knife” or “Navy SEAL Knife” or "Navy Divers Knife".
    They are none of the above.

    It hadn’t been invented yet during Vietnam, and the SEALS and other divers may have used it, but so did a whole lot of other ordinary GI’s.

    They were simply designed as the replacement for the time tested USN MKII (Ka-Bar) as the general purpose Fighting/Utility Knife.

    At any rate, the knife was a failure as a combat, utility, or dive knife, and only used for a short time in the 1980’s & 90’s before it was replaced.

    This one?
    The seller had five of them on eBay listed as a Ca-Bar’s, with a “buy it now” price of $40.00 ea.
    Nobody found the mispelled Ka-Bar listing, they got no bids at all, I bought two of them for $20 ea. and got the pick of the litter.

    According to the seller, a retired Navy man, a bunch of them were in a box of junk he bought at the surplus sale from the New London CT, USN Submarine Scuba Pre-Training school after it was closed down there and moved to Panama City Florida.

    He told me most all of them except the five he was selling had the points broken off, as almost all will have sooner or later if used by real divers.

    This knife has 03 scratched on the blade & sheath. The other one had 05 scratched on it.
    They were supposedly rack numbers used to help the instructors keep track of them when the students turned them back in.

    He also told me the divers hated them because the points broke easily, and they corroded to the sheath springs when constantly exposed to salt water.
    To the point you couldn't get them out of the sheath unless they spent a lot of time cleaning & maintaining them.

    Anyway, whoever designed a combat, utility, or "dive knife" with such a fine needle sharp point like that is beyond me????
    But the whole blade design looks an awful lot like a Russian AK-47 bayonet!


    An interesting thing about the USN Mk3 MOD O Knife is that they are almost completely non-magnetic, although never certified as such.
    A magnet will not stick to this one, and it will not even wiggle a magnetic compass needle when in contact with it.
    Magnetically fused mines and magnetic knives don't play well together I guess.

    Another feature is that the handle and steel butt cap are electrically insulated from the blade & guard.

    IMO: If they wanted to replace the time-tested USN MKII (Ka-Bar) combat/utility knife?
    They should have just up-dated the USN MKII with a stainless black blade, a rot proof synthetic bayonet handle, and a synthetic sheath!
    Pretty much such a knife was already available from Ka-Bar, Ontario, and others, for a lot less money than the Mk3 MOD O + the M9 bayonet combined cost the tax payers I betcha.

    Oh wait?
    The marines did just that with the OKC-3S Bayonet they now use.


    Last edited: Nov 15, 2012
  2. col.lemat

    col.lemat Member

    Apr 3, 2011
    Lakewood, Ca
    I still have my issued KaBar, never did like this knife at all for all of the stated reasons.
  3. Ehtereon11B

    Ehtereon11B internet infantryman

    Aug 20, 2012
    I tried a few of the USN knives produced by Ontario Knife Company. In every instance I returned the knife the same day I received it. You would think that Ontario would have learned something from Ka-bar considering they were contracted to help meet production of "THE Kabar" during WWII.
  4. buck1032

    buck1032 Member

    Oct 29, 2009
    Mk3 Mod O

    I was issued and used the Mk3 when I was stationed at SERE West from 97 to 2000. Alot of the Sailors and Marines I worked with hated the thing. They said that it was a POS and wouldnt maintain an edge. Well I had friends in SEAL Team 3 that taught me the trick to the Mk3. Pull out the metal retention clip and cut out the portion where the knife edge slides into the scabbard. That way when the knife was pulled out or put back in it didnt "cut" into the retention clip.

    As a side note I modified my knife to really suit my needs. On the forward top strap, from the serrations to the drop I hand ground that beveled area down to a nice sharp edge to use the Mag block on. I then shapened the drop down curved portion to a very sharp edge and used that in the cutting and preparation of parachutes. I have had more than one SERE instuctor borrow my knife to prep a chute, and I did warn them of the sharp curve, cut the crap out of thier fingers. LOL

    Anyway, good score on IMHO a good knife. I have been looking for one myself. The old style that is, not the newer one.
  5. Navy Diver

    Navy Diver Member

    Nov 17, 2010
    St Louis, MO
    This was standard issue when I went through Dive School in 1987. I think I still have mine in a dive bag somewhere in the basement. Today, dive knives are open purchased from the civilian dive shops wherever your command is located. You can pretty much get whatever you want. It's not unusual to see a dive side with no 2 knives the same.
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