Opinions will vary by a wide bit. It is most definitely without argument a collectible — two ways because of the odd caliber markings and because of the fantastic PC logo. My best learned opinion would suggest $50-$60 is fair since it is out of package.

Information that is relevant: this is a specially marked 5906 magazine. All 5906 mags run perfectly in the 3566 Limited and all (full size) 356 TS&W marked magazines such as this run perfectly in all the 5906’s and variants.

In other words, it’s an extremely cool collectible, but it isn’t a “missing link” that would make a specific gun work, as 5906 magazines were made by the trillions.

I’d swap you something for it if I had something you could use. If interested, send me a PM.