Can you use 223 and 762x39 in the same gun?

No, you cannot use .223 and 7.62x39 cartridges in the same gun, as they are different calibers with different case dimensions and specifications. Each caliber requires a specific firearm designed to handle its unique cartridge. While some firearms are designed to be multi-caliber, they must be explicitly made for that purpose, typically involving interchangeable barrels or components. Always ensure you are using the correct ammunition for your specific firearm.