At the end of the day it depends on how close to original you want the sheath to be. KaBar has replacement sheaths that will fit your MK 2 combat knife. If you find one that is sterile, ( has no embossing on it), it will pass the ten yard test. By that I mean it wont look out of place being worn by someone looking at it from that distance. At the same time at close inspection anyone who knows what theyre looking for will know its not right.
Ontario is the last company I can think of making this knife under U.S. Government contract. Im not sure that uncle has ordered any recently. Government procurement policy has changed a bit in the last 15 years. You can buy a sheath for their version of the Mk2. I havent seen one up close recently and cant tell you how it compares to the sheaths made during the 1960s. The black color would be OK for a late 60s-70s knife.
http://www2.knifecenter.com/item/ON8181/Ontario-Sheath-Fits-498-Marine-Combat-Knife-Leather
Heres another picture that gives you a better look at an early, ( late 1961 to at least late 60s) sheath.
Officially the government specs effecting the color changed in 1966 from the ox-blood color to black. In practice Camillus continued to deliver knives with the ox-blood color for quite awhile, maybe even to the early 70s. I havent been able to pin it down any closer. If it were me Id try and choose the color of the sheath based on the color of the handle. That can be a little tricky with a knife that has that been there done that character that yours does.
Heres a detail of the sheath construction.
Circled is a wedge shaped welt that is part of the construction of the post WW2 sheaths. Yes some of the WW2 sheaths also had a similar welt in them but not all.
I used two sheaths here. One ox-blood and one black to show how close the color can look under certain light.
If the Ontario sheath I referenced to earlier is still made the same way youd be pretty close to a good match. One thing would be having a new sheath with a used knife. But there are ways to address that which I wont go into.
If after considering the above you decide that what you really want is an original sheath, then consider the following.
First original sheaths can be harder to find than the knife. Good thing is the chances of locating a Vietnam era sheath is IMHO a little better than original WW2 leather sheaths, (note that I said LEATHER).
Gun shows, flee markets, etc., are going to be the likely places to locate these and it can be a big snipe hunt to locate what your looking for. Sometimes your best friend can be members of forums you belong to who have what your looking for and are interested in making a deal.
Regarding what your referring to as a plastic sheath. I believe your talking about the (U.S.N./MK.2) scabbard.
This scabbard was made during WW2 to fit the mark 2 combat knife for the Navy. They made a lot of these and a lot of them were in the Navy supply chain for a very long time.
These are best paired with a U.S.N. marked WW2 combat knife. The Marines didnt officially adapt this scabbard, but Id not be surprised that more than a few Marines used these.
It also wouldnt look out of place to see a picture of a Vietnam G.I. wearing one of these at that time but it wouldnt be common to issue that combination to him during that time period.
While these scabbards are starting to get harder to run across on the open market now it may be that youll run across one of these before you find a correct leather sheath.
FYI here are some pictures of a couple of WW2 Camillus U.S.N. mark 2s to show you two different ways they were marked at that time.
If your really interested in collecting U.S. military blades Id recommend youd invest in the book; The best of U.S. Military Knives Bayonets and Machetes by M.H.Cole) Its still currently in print and its a bargain for a reference source. If you dont want to go that way try the library system to see if you can find any of the Coles books. There are other resources too, but this is getting off topic here.
Sorry for the long post. Hope this helps.
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