Nathan: Yes you can, but it's not wise to do so.
Chawbaccer: I had never heard of it until I did it to my own gun. I was too cheap to go buy another barrel and I didn't switch the choke and put probably close to 500 normal 1oz slugs through the gun. (Not in one day though!) When I went to a trap range in the fall that featured some "longer range" trap shoots (pretty neat) I noticed that I couldn't hit a thing when they clays got out there. I made sure I had the full choke in and still couldn't hit a thing. When I got home, I took a micrometer to the choke and the constriction was only .012" (a full choke has a typical constriction of .035" while an IC choke has a constriction of .010".)
I bought a cylinder (no choke) barrel after that and it works as a HD barrel and a rifled/foster slug barrel.