If I use a 77mm wide angle on a 58mm cam with an adaptor

I believe the 58mm will give you a wider angle. Shorter focal length=wider angle, right? I could be wrong about that.

 

I would think the same, but then again, I'm still selfstruggling with all those different lenses.

 

Yes, shorter is wider. How wide will depend on your sensor size, (77mm is not 'wide angle' on 35mm format, focal lengths of 35mm and shorter are). What camera are you using?

 

Wait, I don't think he's talking focal length. More like ring diameter.

Right?

So you'd buy the 77mm-thread wide angle thing, and then a 58mm->77mm step-up ring. No change in view assuming the glass is the same magnification between the 58mm lens and 77mm lens is the same.