how would I add half a sphere to a square mesh?

Im about two weeks into blender, for a first project I wanted to do something simple, a bullet. As I was working on it I noticed from reference photos that the center piece where the pin hits the bullet it is not exactly flat but more like a flattened hemisphere. Made me wonder how I could put one there. of course on my project the backside of the bullet was made from the cylinder.

I know how to cut a circle into a cube.
would like to know how to add or develop half a sphere onto a non circular mesh, say the side of a cube, or a grid / plane

You can create a half-sphere from a full one and then join it to the cube, if that will do, but i don’t understand why you’re using a cube or non-circular mesh at all.

Use subtract option of boolean tool. Insert a full sphere into the side of your cube and subtract the sphere from the cube.

Like this?

https://lh6.googleusercontent.com/4v-GBhkdJvBmR0V4chLYrpOKIWx2RXWazjognyxWe_iX7hSNm9G0bk2Lf1Uegw3qn6pmwg=w917-h793

It’s not quite a sphere to square, but the principles are the same. Ideally start with a Round Cube or PolySphere as it’s also known as…

If you’re absolutely unsure how to do this then let me know and I’ll make you a brief tutorial when I get home.

guess im just curious, right now im experimenting, trying ro learn as much as I can about the tricks of modeling, cant seem to find tutorials that are just above newbie level. everything is far more advanced. I probably could find the tutorials if I wanted to pay for them, but that just doesnt seem right.

sounds interesting, but couldnt find polysphere anywhere