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This SBA was among the last batch I got, and the more I look at it, the more it's puzzling. Sure, it's a little beat up, but the specs are weird:

Weight: 7.5 grams (normal is 8.1g)
Diameter: 25mm (normal is 26.5mm)
Edge: Twice as thick as normal (3rd photo)

...and it has an odd ring to it. Thought counterfeit at first, especially since the lettering looks a bit crude, but that might be because it's so roughed up.

Could it be struck on a foreign planchet?

Post mint damage? Yet the devices don't appear deliberately marred in any way.

Thoughts?

Wow, weird! I thought they were '79 only.

My guess, yes foreign. $$$$$$

I’d take it to a dealer who knows errors well. Potentially, it might be worth sending in to get certified.

Many years ago, I had a blank planchet that was from 1856-64, so it was either a Flying Eagle or early copper nickel Indian cent. It came back slabbed by PCGS and someone from PCGS told me this was the only one like this they ever certified!

Sadly, it was stolen from my storage locker in November, 2019.

Small possibility, but it might be a shrunken coin. A coin is shrunken with a high voltage electromagnet. They are for sale at capturedlightning.com

Thanks for the suggestions. I'll bring it to a coin show this August and see what a few experts have to say.

Never seen those shrunken coins before.

Anyone know of a source that lists the coins the US minted for other nations?

Here is a checklist af foreign coins struck at US Mints:

https://libertycoinservice.com/wp-content/uploads/learning-center/collectors-checklist-foreign-coins-by-us-mint-type.pdf

I also did a search on Numista for any CuNi coins weighing around 7.5 grams from 1978-1984, and the only one that matched was a Poland 10 Zlotych.

https://en.numista.com/catalogue/pieces3283.html

But that coin wasn't minted at US Mint.

Thank you!

I am in the shrunken coin camp.