I saw Browning 725 field in a shop for 1700, but he receiver area is stained or corroded. 28 inch barrels, 12 guage. I dont know if it is coated or stainless. Could it be buffed or sanded out?

Imo, very unlikely that it would ever look right.

Maybe try some Flitz. It's good stuff. I don't think the Browning has a stainless steel action.

I handled a new (off the rack) 725 Field last week and it was priced at $1999.99.

That stain won’t get better.

$1700??
I'd offer him a grand tops. That's ugly and will never look good again without spending a lot of money.

I was told it is a metal coating over the steel, so it would probably rub completely off until the stain was gone. I am going to pass.