Hey AA..
Yes,, this is true,,with the washers sandwiched in between you get sort of a shock absorber effect, which can save the sheath from damage if it gets caught on something..
A little give is good to have, and also a little space behind the clip is also good to have....
Is the sheath flat on the back side,,or is it molded as well ??
What kind of foam are you using..???
ttyle
Eric....