i have a 500 with changeable chokes. Which one would your recommend for a rifled slug

Naturally a fully rifled slug barrel is going to be better,but if for some reason you HAVE to use same barrel that's fitted for screw in choke tubes(accuchoke in mossberg I believe),go with a rifled choke tube-extended if possible.

If a rifled tube isn't an option, go with the most open choke you can find. Many smoothbores shoot very well (mine included) with an Improved Cylinder tube or Skeet if you have one. You'll have to use Foster type slugs with it.

Improved Cylinder is prefered for rifled slugs. You can get a rifled slugs if you want to shoot sabots.

Did you mean rifled choke?

Thats what i thought he meant.

Sometimes, a rifled choke tube works wonders with accuracy, but sometimes they don't prove as good as a plain smooth bore. You never know until you try one!

I had a 12-Ga.Ithaca Deerslayer once that was actuallly boredto about a 14-gauge diameter for whole length of the bore. The best shooting slugs in this gun were those of .690" that came in the Remington brand. They just fit the bore tightly! That smoothbore was able to shoot 3", 3-shot groups at 100 yards (it had a 2.5X scope on it).

Today, I would get a couple of different slug brands,take one shell apartof each make, and see which brand slug fit tightest in one of your choke tubes. I would then use that brand with that choke tube and test to see how it shoots.

IF the slugs gave a tight sliding fit through the tube constriction, I'd bet they will shoot tight groups (3"-4"@75 yards).