Just got a new Remington 870 Express Magnum with a 28" bbl and a modified choke (screw in). Can slugs be fired through that barrel without screwing up the choke? If not, is there a screw in "rifled choke" that should be used with them, or will the IC choke handle slugs? I ask because, although the 28" bbl is mainly for bird hunting and similar shotgunning tasks, I want to use this gun for IPSC (with an extended tube of course) and occassionally slugs will be included in the COF. Thanks in advance for any advice/experience.