I have never seen a cartridge made in China with such a neat and evenly applied color! How much heavier than a standard blank? 31 88 is a common headstamp on these (normal) blanks. Perhaps it is someone’s fantasy load made up from a common item? The weight issue is puzzling, suggesting a heavier charge for use as a grenade launching cartridge.
Never seen or heard of that one, I’d be very skeptical. How much heavier than the standard blank load? The paint itself could account for a few grains.
The vendor said this came packed with a special AT grenade. I have not weighed it but it feels heavier than the similar blank.