Thanks, battlemunky, for asking me how it worked out. Your email helped me get back here to this post. I don't spend enough time navigating the site and I was having trouble finding my way back, so, thank you for that! I wouldn't have given up, just for the record. I'm big on contributing as much useful info as I can, no matter what forum or website I'm on. I've been the recipient of so many good tips, etc, that I feel obligated to contribute. I say this to anyone who doesn't contribute. You know who you are. : )
Here's where it sits right now. I was afraid of getting carried away so I didn't take it completely flat, but flat enough to make a difference. Plus I was using an angle grinder. A "burning flesh" smell lingered for hours afterward (I got burned once, and although the mallet is made of rawhide, the smell was similar to what I remember. A kind of sweet and sickening stench that you can almost taste. But I digress... )
The mallet came out just fine.
After:
and Before:
Both ends were deformed similarly.