I talked to the local police firearms instructor ... He told me and open choke or cylinder choke...or none at all. I really don't know what to think about you guys. I'm signing off this board...........No thanks
What makes you think your "local police firearms instructor" is automatically the guy with the single unarguably correct answer and everyone here is trying to steer you in the wrong direction? That's silly. Every post I read in the thread was helpfull and your lack of knowledge about slugs are what is misleading you.
With the answer he gave you I would be willing to bet he was just giving you a general answer "since you asked a general question" or just maybe he does not have the same experience level shooting slugs that the kind members who already tried to answer your question has.
Here is the simple answer and why. What ever choke tube comes with your shotgun will be safe to shoot rifled slugs and will work just fine.
So the big question is why? One of the biggest misconceptions about rifled slugs also known as Foster slugs, come from the name "rifled slugs". The name rifled slug would lead you to believe that the rifling on the slug causes it to spin when fired since the barrel is smooth, but actually they are there to reduce friction (increasing velocity) and so the slug can easily be swaged down (deform) as it passes through a choke(constriction). That's why it is safe to shoot it through any choke constriction, from cyl to full.
Obviously by your wording you don't realize just yet that open, cylinder, and no choke at all mean the same thing, the choke tube has no constriction. You saying no choke at all has me a little concerned. Just in case you don't know, that does not mean no choke tube in the barrel, it means that the choke tube has no constriction, if you shoot a slug through the barrel with out a choke tube installed it can mess up the threads.
So, I'm not saying a cylinder choke tube is a wrong answer, actually it is probably the best general answer since the slug does not need to deform at all when it passes through the CYL choke since a CYL choke tube has no actual constriction.
Hypothetically you would think this would automatically make less choke more accurate shooting but in actuality, as others have pointed out sometimes that's just not the case. You may find that Improved Cylinder (very little choke) or Modified (medium choke) may shoot better groups with a certain brand of slugs. There is no way to know what combination of barrel/choke/brand of slug will shoot the best out of your barrel unless you test each of them for yourself out of your own barrel which is what everyone here was trying to tell you.
Testing each combination to find what the most accurate can end up costing more money than you may be wanting or willing to spend, it is also a pain in the butt not to mention shoulder.
The cheapest route you could go would be to just try out a few different brands of slugs though what ever choke comes with your shotgun.
If your not happy with the accuracy and you was wanting to "BUY" just one choke tube, only for shooting slugs, hoping for the best accuracy with no intention on trying to test others I would buy a rifled choke tube. Yes they are made to shoot sabots but it's perfectly safe to fire rifled slugs in a rifled barrel and I have found they will also shoot the rifled slugs pretty darn good too without much leading. Not to mention if the rifled slugs are not giving you the accuracy or range your looking for you could always try out the sabot type slugs.
