The .357 magnum round out of a carbine is more powerful than a 30 carbine round at all distances. For a quick and dirty comparison I pulled up the ballistics on both rounds from the winchester site.
Rifle Ballistics for .357 magnum with 158 gr. Super-X® Jacketed Soft Point
Distance (yds) Velocity (fps) Energy (ft.lbs.) Trajectory Short , Long (in.)
Muzzle...............1830...............1175............................-..............-
50 - - 0.0 -
100...................1427................715..........................-2.4 ............0
150 - - -9.1 -5.5
200....................1138...............454...........................-21..........-16.2
250 - -- -39.2 -33.1
Rifle Ballistics for 30 carbine with 110 gr. Super-X® Hollow Soft Point
Distance (yds) Velocity (fps) Energy (ft.lbs.) Trajectory Short , Long (in.)
Muzzle...............1990..............967.................................-...........-
50 - - 0.9 -
100...................1567..............600................................ 0.......... 0
150 - - -4.5 -4.5
200...................1236...............373.............................-13.5.....-13.5
250 - -- -28.3 -28.3
And yes, these are rifle ballistics, not pistol. For comparison here are the pistol ballistics from the same web site.
Handgun Ballistics for .357 magnum with 158 gr. Super-X® Jacketed Soft Point
Distance (yds) Velocity (fps) Energy (ft.lbs.)
Muzzle...............1235..............535
50.....................1104..............428
100....................1015.............361
And just for fun the energy levels of a 44 magnum out of a pistol to compare it all with using a 240 gr. Super-X® Hollow Soft Point
Distance (yds) Velocity (fps) Energy (ft.lbs.)
Muzzle........................1180......................741
50..............................1081......................623
Notice, the .357 magnum round out of a lever rifle has more energy at the muzzle than a 44 mag out of a pistol does. In fact, it has almost as much energy at 100 yards as a 44 mag does at the muzzle out of a pistol. I've never heard anyone complain about their 44 mag revolver not having enough "take down power".
Is the .357 lever gun as powerful as a real rifle round like .223 or .308? No. But it IS a decent carbine round, as carbine rounds go. Although a lot of people will tell you there are better SHTF rifle choices out there, and there are, I don't think it's a bad choice to make. Especially if you don't shoot rifles much and already own revolvers in the same caliber.
For more extensive discussion about this topic check out the armory subforum of
http://neardeathexperiments.com.