metal cutting circular saw

Not necessarily. Tip needs to be clean and you may want to try slightly different pressures on your regulators and clean the tip. Did I mention the tip needs to be CLEAN :)

See this recent Instagram post Issac put up:

If you want clean torch cuts read the tips in his posts. He also posts under Torch Norris:

Harbor Freight used to sell one of those saws for metal. Looked like a Skill Saw but with extra shielding. Think it was discontinued...

A so-called cold saw might make a lovely cut, but workholding and vulnerability to inclusions are scary aspects. You've left out one other cutting option, friction blade in a circular saw; the idea is that a moving disk can cool its edge, but the workpiece just keeps getting hotter, until it burns. It's not expensive, and works in a variety of table, chop, or radial saws, if you can stand the sparks.

It does take large diameter blades (not gonna work in a handheld saw).

Me, I'd prefer to find a steel supplier that can do waterjet or laser cuts. That solves straight, curved, holes, maybe bevels and other fancy stuff.

Though I haven't used one a friend of mine who just retired from a boat building place saw these used quite a bit. He said they worked well on 1/4 inch stuff, were noisy, and had lots of hot chips. But they could do long cuts. But only straight cuts. A plasma might be more expensive but boy, do they cut a large variety of metals. And fast. On the other hand, they generate lots of fine metal oxide dust. Not the best stuff to breathe. Eric

A local welder has a DeWalt. He cut some 1-1/2 x 3/8" bar stock on it for me, and it went pretty quickly. These are high-speed but aren't as noisy/messy as regular circular saws. Cold saws are better but $$$

Agreed.

I love plasma, now that I've used one at my friend's shop. Very, very cool tech. I wonder how well the $179 ebay special would hold up... not for half inch stock, though.