Most BSA functions are indeed no-firearms affairs.
Cub Scouts (6-10) still familiarizes younger boys with air rifles. Boy Scouts (11-17) has basic marksmanship training with .22 rifles and small-bore shotguns. Exploring (now a coed, career exploration-only program) for ages 14-20 allows Law Enforcement Explorers to train with all law enforcement firearms under the direction of the law enforcement agency that sponsors them, and Venturing (coed, 14-20 [think old High-Adventure Exploring]) allows those Venture Crews which register with specialties of hunting, Black Powder, historical reenacting, and firearms (any and all) to use firearms appropriate to their special interests. This "graded" approach deals with what BSA determines to be the "age-appropriateness" of the activities. Many here may believe, and rightly so, that their son or daughter is mature enough to start these firearms activities earlier; but since BSA deals with large groups of young people who vary both by age and by maturity level within the same age group, BSA has decided strictly to limit firearms activities to the areas listed above.
Otherwise, firearms, as in open or concealed carry by Scouters, for example, are prohibited.