I couldn't say if the copper plated zinc coins leave the mint that way or if the bubble(s) take time to show or form.
I'm surprised they've stayed in tack this long and suspect they may have had a helping hand after minting, but have no clue as to how at this time. Thanks, Doug.
Disclaimer: While a tremendous amount of effort goes into ensuring the accuracy of the information contained in this site, Coin Community assumes no liability for errors. Copyright 2005 - 2026 Coin Community Family- all rights reserved worldwide. Use of any images or content on this website without prior written permission of Coin Community or the original lender is strictly prohibited. Contact Us | Advertise Here | Privacy Policy / Terms of Use