You didn't specify model, however, I would assume 870? I have an 870 Remington Wingmaster, circa 1974. 28" barrel. If I could hit the ducks with pellets, I'd swing the barrel at them! I bought a "Police barre" and unscrewed friend cap and stuck it on for home defense.
If your Remington is in good condition, I wouldn't mess it up. Just buy a 18" barrel for it. A few years back, I purchased a new 870 Police Special. Comes off Remington Police assembly line. A proven performer.
It's been so long I forgot what model it is. Probably the 870 Wingmaster. But the full choke barrel is long enough that I could swat ducks with it if I missed the shot. I've seen muskets with shorter barrels.
All kidding aside thanks all for the recommendations. I'm a cheap b*sturd and would rather not by another barrel. Seems alot of peoples weapons end up in the lake. Odd.