You can shoot slugs out of your shot gun and oo buck no problem fire away, I would leave the Full choke with 1 Slug in the chamber then follow up with OO buck for if you had a bad shot or the decide for what ever the reason. I wouldnt waste the money on a slug barrell. Maybe find a used slug gun for sale, they can be found quit often especialy after deer season since the city slickers only hunt every so often..

my opinion shooting slugs at 150 yds. with out a scope is a little desperate! Better have a scope to improve the chances, but then again I still thing it is to far. I wouldnt go past 100yds. with a slug or buck shot, I did some testing last year with the 23/4 OO, at 80 yards and it was plenty good enough to shoot deer, 6 out of 9 pellets would get in a paper plate. The only reason I would load up a slug for the first shot is it I think if positioned correctly would be more damaging then follow up the OO...