I have one small one that I enjoy. Unless I am mistaken, they normally have a conical shaped bowl. In my experience, if you are not accustomed to them, conical shaped bowls have to be packed much lighter and discretion must be used with the tamper compared to straight sided bowls. The bottom will compress to a higher degree, clogging the airway and leaving a wet mess. @freestoke 's musketball method works perfect in a cone. Just wad a ball of baccy up and shove it in the top, making sure not to cram it all the way down. The taper at the bottom leaves a nice little air pocket and as you (lightly) tamp the baccy will make it's way to the bottom.