I believe it max. PSI. Not sure. I don't remember offhand but I think the shells I shoot come out of the barrel at like 1500 feet per second. I could be wrong.
I shoot mostly modified choke from carlsons. http://www.choketube.com The birds are fast and about 30-35 yards out. I shoot 1 oz max dram 8's. and it gets the job done.
I don't think you can do what you want to do with the gun.
It will be hard to find the barrels you want to get anyway. If you got the rifled sight tactical barrel, you could do what you want, if your could find the barrels.
Who said they use #9 shot? Who said I was insulted about people using birdshot? I do think its very wrong to have a picture of a baby looking like its dead in that carseat. I think you know a lot about guns and ammo. I think you need to grow up a bit.