What should I do if wire gauge is too large to fit into a screw terminal?
If you are using #10 stranded under a screw using a crimp terminal will be the easiest and safest connection.

For that size and application you'd want to use a yellow fork terminal.

Here is a good tutorial: https://learn.sparkfun.com/tutorials/working-with-wire/how-to-crimp-an-electrical-connector