Abstract: Shotshell type ammunition includes a hull, a wad member disposed within the hull, and at least one projectile disposed within at least partially the hull. The hull has a rimless proximal end that includes a primer for firing the ammunition. The hull also has a seat surface for seating the hull against a complementary seat surface in a firing chamber of a firearm. The seat surface is located a distance from an outer end surface of the hull at the rimless proximal end. The hull further includes an outer side surface extending from the rimless proximal end of the hull to the seat surface of the hull. Methods of fabricating such ammunition include forming such a hull, and providing a wad member and one or more projectiles at least partially within the hull.