SMG and shot gun are very equal. all guns are as equal as the chance of rolling a combined total of 7 with a dice. Shot hun is infact better than smg at long range.Smg is only betetr than shotgun when the smg user gets the jump on the one with the shotgun. all guns are equal. it just depends on who is using the weapon. The reason some one misght say that is because most people don't use the sights when it comes to the shot gun.
ALL IM TRYNG TO SAY IS IT DEPENDS ON THE SKILL LEVEL OF THE ONE WEILDING THE WEAPON.