Ratweilers are one of my favorite Busse designs. I have 3 so I measured them. All are coated. 3/16 measures .190”
First generation measures .240”
Later 1/4” measures .259”
The 3/16 is my favorite
This is what I get as well when I measure mine the newer RW is slightly thicker.
My skinny is silver coated and measures .190"
Over the last 20 years I have seen some outliers in the same models.
But generally with 1000's of sheaths made they are very few that do not fit like the ones I made the sheaths with.
Some Busse's can vary in the early days back in the Basic 5 days and original E handles.
I had 2 basic 5's vary .5" in length
I had a couple E-handles vary in thickness.
everyone of the old HOGs may remember the tweeners Meaner Streets ?
But again for the most part most of the knives were exactly the same.
Now (the last 12 or so years) they are all pretty much exact.
You must have a very rare one
In kydex .01" or one hundredth of an inch can make a difference between snug and tight.
and absolutely everyone has a different definition of what tight is
I use blue painters tape on all the knives I make sheaths for to give a little room but each layer is only about .005"
Yes two layers would add maybe about .01" but through molding compression and such things it is not an exact science.
Also I have found on different blade lengths more or less tape is "correct"
On the saw backs 1 layer is what works best 2 layers and it is too loose (another very subjective term)
On the Butaniku 8 layers per side is the minimum
TG and RW's 3 layers
and so on.
Also if 2 layers of blue tape were added it theoretically could add .01" but then it would then only be to the thickness of the blade in this case.
Add 5 layers per side and it may be enough ?
But there is still the compression factor and it would be a guess.
To make a kydex sheath for this outlier it would be best to send it in.
Hope this perspective helps.