My cylinder bore HD 870 patterns one brand 00 into 20-24" at 25 yards, but it has forcing cone work and does better than most. I may get the thing tubed one of these days, but admit it runs low on my priorities.
Darn near all shotguns can use a touch of choke to round out the patterns, straight cylinder bore patterns are kinda erratic. Even .0002-3" will usually help things out. In fact, most "Cylinder" bores have that much.
In this case, I'd go for a tubed bbl and experiment...