I own an Ithaca 37 12 ga. w/smooth bore.....Given that, I was told to try different makes of Foster slugs (the ones with the rifling already on the slugs) and see which ones work out the best for accuracy. Brenneke's were the original and I hear still the best (expensive). I've used ACTIV's but they're no longer made...so that leaves the Rems, Federal, Winchesters, etc. As far as the Poly Choke is concerned, try the IC or Modified, as that's what choke my Deerslayer Barrel is. The foster slugs are made w/pure lead so they should be safe to use and will deform to the choke you use (.010'' to .020" under).
Secondly, make sure to keep your barrel clean and free of leading which will happen rapidly w/ foster slugs(about 2 boxes will do it!) Use that bronze bore brush and lots of bore cleaner and clean, clean, clean. I use Outers Solvent.
Third, keep the barrel TIGHT against the receiver. Don't let any play develop after you clean the barrel and re assemble. Do you have rifle sights or Red Dot Scope?
Should you buy a rifled barrel? I'd try your smooth bore first and then decide. Sabot slugs have made some great claims, but see how the Mossburg handles the Fosters first. Just my 2 cents!
