It may well be as successful as the Medusa M47. That revolver was chambered for .357 Magnum and could chamber and fire many rounds smaller than the .357 Magnum. With projectiles in the 9mm range the accuracy was acceptable according to reviews.
Having ammunition and a gun designed and zeroed for that ammo has also the advantage that you have a fairly good idea about the point of impact. My main hunting rifle does not even shoot all loads of the caliber itīs chambered for reasonably close to the point of aim for my hunting ammo.
If you are carrying a gun for a survival situation it might be useful to be able to hit something smaller than the proverbial broad side of a barn.
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If it isnīt broken, it doesnīt have enough features yet.