For one thing, ammo is much cheaper than barrels or even choke tubes. Find the choke tubes that are indicated for the type shooting you do and pattern them with your favorite load. Sooner or later, you'll hit a combination that is ideal for your gun. Shotguns begin to get load-sensitive at modified choke and get more so, the more you tighten the choke. Patterning a shotgun is something the average hunter never does.
All shotgun hunters intend to pattern their gun someday, but someday never comes.
In fact, most hunters don't know if where they are aiming actually is where the gun is shooting. Since they shoot instinctively, without aiming, they assume the shot charge is going where their eye tells it to, but if the barrel is bent, it may not be. If your favorite turkey gun has a wayward barrel and you're shooting a fist-sized shot pattern at birds, about the best you can hope for is that you'll scare a bird to death. Maybe the hunter's barrel was bent. It doesn't take much to throw a gun off.