I've come from the old school of shotgunning where you did your gunning from a fixed choke barrel or you had a poly choke on the end of the barrel. In either case I've never had a problem shooting foster slugs out of either type of shotgun. Within the last three years I have either won or purchased 4 different, more modern shotguns and all of them have the screw in choke. The question I have for all of you is, is it safe to fire foster slugs out of any barrel with a screw in choke. My Mossberg shotguns do not recommend doing so and I was just wondering if that was so they could sell more barrels or is it a legitimate safety concern?