James, they can be fired, but most likely won't cycle in a pump or semi-auto. If you have a break open shotgun, they will work no issues.
Stay safe & have a great day!

Hi James and welcome. You will need to test them in your shotgun. There is an adapter for Mossberg Pumps : budsgunshop.com/product_info.php/products_id/36595/opsol+texas+miniclip+mini-clip+for+mossberg+500+590+12+gauge+1+round+polymer+black+finish --------- Any other model, just test them. Cheers and stay safe!

There is an adapter for some shotguns. Search adapter for shotgun mini-shells.

Mini shells were initially advertised for use only in breech-loading shotguns because they don't typically feed reliably in pumps and not at all in semi-autos. Some pump actions handle them better than others. They tend to do okay if you run the action slowly and deliberately, and keep the gun perfectly upright. If you have a Mossberg 500/590 then you can use the Opsol mini shell adapter.