The cover art for the base game show an epic battle on a train between an unspeakable horror and a guy with a tommygun.
Was there are tommygun in the base game? No. Was there one in the next 3 expansions? No. Why include the most iconic weapon from the time period and the one you advertise right on the front of your freaking box? Accurate advertising is for sissies.
But there is now. Sure it has the exact same stats as the carbine rifle, and you could have strait up replaced it with that weapon in the base game and changed nothing from gameplay and waited till now to release the carbine rifle but you just had to keep us waiting.