So I picked up a stripped P226 slide that potentially has an interesting history.... I would like to build it out into a usable gun, and I need some advice.

Can I buy a Sig Legion and simply transfer the guts into this slide and have it work, like an AR15?

Or if I were to buy a used Sig P226 as a donor gun, is there anything I should look out for, or avoid? And is there a Rob Roberts/ Turnbull of the P226 world that I should send it to for refinishing and a buildout?

This link mentions Robert Burke and Bruce Gray as potential gunsmiths....

Best advice I can give you, buy the gun not the story. A place that sells parts telling a story how they found a box labeled CRANE P226 slides and then confirming they are from Crane because they talked to some SEAL and some FOIA document that is cut down and doesn’t show anything matching and then add in the claim that the slide you will get will look the same “or better” while not photographing their best looking slides.. The whole thing is dubious.

These slides will need a lot of work to make them function again and are not compatible with current slides. You can’t just move the parts over from a current production P226 to this slide. It will need parts that are no longer made and getting harder and harder to find. You’ll need a new breach block assembly, breech block pin, firing pin. You be buying a really expensive slide that has a neat story that may or may not be true and it certainly makes older slides that have parts that are no longer in production and quickly becoming obsolete, look more attractive to buyers. I wouldn’t touch these slides even if they were half that price. Good luck with it though.

Too bad they didn’t come with a barrel, frame, and matching serial numbers. That’s where the value is, if there is any.

Agreed.

That's assuming you have documentation proving they were within a known NSW serial number range.
Then you've got to find a buyer who cares about any of that.

These were just COTS purchases, so they're no different than any other P226 from that time period.

If you really like this slide the easiest and probably the most economical thing to do would be to find an old folded slide complete 226 and swap all the parts in the donor slide into your special slide. Then you'll have a complete gun,

Sourcing individual parts like the breach block, old frame,  etc may be difficult, expensive and time consuming.

This is the kind of advice I'm looking for. I was unaware there is that much of a difference in P226 iterations over time.

For the guys saying a slide isn't "collectible".... I'm not doing this with an eye to resale value down the road. It's just interesting to me, so I figured why not.