12 ga slugs work well to bust locks and hinges. SMGs don't
It is true that SMG's are not practical for breaching applications. However, a standard 12 ga slug used for breaching locks and hinges can be very dangerous for the operator and team members due to mass fragmentation of an exploding slug when impacting upon metal locks and hinges. A breacher wielding a shotgun carries a breaching round called "Hatton". It is a fast disintegration material similar to filling material a dentist would use to patch your teeth.