A Mad Dog knife WILL withstand anything a protected human can deal with. As a test, Hilton Yam drenched an ATAK grip in gasoline and lit it; five minutes or so of burn didn't affect it. The sheath is another matter, Kydex starts to go limp in the steam from a teakettle spout.
Kevin probably could make a sheath out of that grip material. Might be pricey as hell though...he's a materials scientist, so he might be able to thunk up something else.
Leather ain't gonna cut it. Nomex cloth epoxied into something resembling fiberglas maybe? Or...aren't there some oddball higher-temp Kydex formula variants out there, not commonly used in sheathmaking but...for a fireman, might be a godsend?
Check with Kevin, or perhaps Scott Evans of Edgeworks might know something:
www.tacticalholsters.com
One thing about a Mad Dog: the toughness of the knife itself is just completely out there. One test recently performed showed that an untrained cop with an ATAK 7" Mad Dog could punch a rectangular hole in the roof of a crashed car big enough to haul the victim out, and doing so was *faster* than waiting for a Jaws Of Life crew to come out and do the extrication. Understand here, that assumes the knife has a "head start" of around 10 minutes or so because it was presumed to be "on scene" either carried by the officer or in his trunk.
If I was in a fire and needed to rip through sheetmetal in a big hurry, there's nothing I'd rather have with me. The ATAK is probably the best model and possibly the toughest single-edge utility knife ever made, period.
Jim March