There are a few variations on the Remington 581/ 591 rifles converted to small CF rounds.
Since 5mm rimfire ammo is a bit tough to get (supposedly there is some soon to come out of Mexico, if it gets imported here. Or maybe it has been already, but whatever..) the rifles have not gotten much use over the years. Maybe you have one living in a back corner of the safe, maybe not. And maybe there are still a few around that are simply guns that cannot be fed, rather than "rare and collectible treasures", if you know what I mean.
Calhoon apparently has conversion instructions for use with his .19 Calhoon (Hornet based) but it should be within reason to use the same setup for about any small case, similar to the CCM (velo-dog based, iirc) Cooper cartridges.
Just gotta get one of the Remington's, build a new front end for the bolt, and thread the front of the action, and, and, and... Well, you know how it goes.
Not exactly a reversible mod to the gun.
There is a build documented on the Homegunsmith forum, and I think one other forum, Small Caliber, maybe, that I ran across a while back. Supposedly, the Remmy's were proofed to 60K psi, so they were plenty strong.
Who care what the 5.7 was designed for! What matters is what it can be used for! Cheap shooting, with decent performance!
Cheers
Trev