Pistol caliber carbines such as the Marlin Camp Carbine, Ruger PC series, Hi-Point 995, and Beretta CX4 are very popular with shooters. The capability to have a longarm chambered for the same rounds as your handgun and in some cases even use the same magazines is very handy. With a longer barrel and better sights coupled with a sturdier two-handed grip, these pistol caliber carbines are capable of making long range shots more accurately. It is even banded about that pistol caliber carbines provide an increase in round velocity. There is an argument in some gun circles that state this last factor to be a myth. Others state that on average the carbine increase is only about 10% in velocity. Let's take a look at the documentation.
Yankee Gun Nuts Testing
Well the gang over at Yankee Gun Nuts has done some field-testing with pistol caliber carbines and what they have to say is interesting. They took a Glock 23 (.40S&W handgun with a 4" barrel) and a Ruger PC4 (.40S&W carbine with a 16.25-inch barrel) and tested six different types of factory ammo from three manufacturers. All loads clocked faster in the carbine than they did in the handgun. The increase was typically only about 100fps or so in terms of velocity-- not a huge differences but definitely some hard numbers to chew on. The best performer was Hornady's TAP FPD 155gr ammo that produced an increase in 168.2fps and added a hefty 142 ft/lbs of energy.
Ballistics By the Inch testing
Still don't believe in the ballistics fairy for pistol caliber carbines? Head over to Ballistics by the Inch, where they have greatly expanded the tests from Yankee Gun Nuts. In the 40S&W, they show the documentation of how 11 different loads work inch-by-inch from two-inch snubbies through 18-inch carbines. For some the increase is marginal such as Speer's 180gr Gold Dot which produced 175fps extra from an 18-inch carbine over a 2-inch snubby. Some however are scorchers, gaining more than 500 extra fps.
Bottom line is, Yes, Virginia, pistol caliber carbines do hit harder in the same caliber than pistols; however, your mileage may vary.