So if it has bead sites, does that mean it is not meant to shoot slugs?
First let me say, good choice! ;-) Course I'm biased, I bought my Mossberg 500 in Oct last year, with both a 18.5" Cylinder (smooth) Bore and 28" Vent Ribbed (Improved Choke) last year - and am very happy with my purchase!
#1 - "bead" sights don't have anything to do with being able to shoot slugs or not.
#2 - slugs (1 single BIG bullet) - means it needs to be able to "get through" the choke. (see the cheaperthandirt.com link previously - as to what I mean)
a. Since there is NO choke on a cylinder (smooth) bore. It's a very good choice to use for shooting slugs (I generally shoot rifled slugs 1oz - 2 3/4") very very accurate with the 18.5" barrel.
b. Since the 28" VR barrel, is an "improved choke" - you will also be able to shoot slugs nicely from that barrel as well.
NEXT, on my end... when the shotgun is at home - it sits with #00 buck, and the 18.5" barrel attached. Home defense, or close quarter shooting is what I intend it's use to be... if anyone is stupid enough to try and get past my 120lb Great Dane first..
The 28" barrel, I use for clay pigeon shooting. And I added a 24" fully rifled w/scope barrel for long range shooting w/slugs or sabots.
Enjoy your upcoming purchase!
-M3