Mook claimed to have an original spandrel.  Spandrel?  I think that is what it's called.  A core around which one beats something into submission.

I have a few with dents.  One of these days I should see if i can snag a really bad one to see what would be required to disassemble and reassemble it.  One would have to be really bored but a brass sand cast spandrel would be handy.

I have one of those real early M-1910 "spun" canteens with some dents.  Same problem really outside of the neck being smaller.  Hydraulic pressure would be the way to go with that.  Without disassembling a Krag scabbard hydraulic pressure would also be the way to go.  Assuming one could make such a thing. 

ACME Scabbard Repair Works.  A subsidiary of Road Runner Industries no doubt. 

I'll troll eBay for a really bad scabbard and take a poke at one missing the handle.  Won't hurt to sacrifice such a thing.  Maybe it'll be instructive on how to attach those also.