MOSSBERG 500 SLUG BARREL & SCOPE 12 GA. 24 IN. BLUE This Mossberg shotgun barrel is a 24� 12 gauge barrel with full rifling. This package also comes with a Bushnell 3-9x32mm scope mounted on the integrated scope mount. The scope features Bushnell Multi-X reticle and fast focus eyepiece. This barrel fits Mossberg 500 and Maverick 88 6-shot models.