In the end gentleman, I think the guys at Real Guns, in their article Ruger's 30 Carbine Blackhawk, got it right:
The 30 Caliber carbine holds only 2 grain more powder than the diminutive 327 Federal Magnum and 4 grains less than the mundane 357 Magnum. However, seat typical bullets in all three and the long overall length and long cylindered .30 Carbine has a net capacity 2 1/2 time greater than the 327 Federal magnum and only half a grain less than the ubiquitous 357 Magnum. The 30 Carbine also packs more pressure than the other two rounds with 46.4k psi, compared to 44.9k psi for the 327 Fed Mag and 35.0k psi for the 357 Magnum. If the 30 Carbine poses a challenge, it is identifying a powder that will burn efficiently within a revolver's relatively small bore volume; at equal 7.5" barrel lengths expressed in cubic inches of volume: 30 Carbine 0.559, 327 Fed Mag 0.630, 357 Magnum 0.751.
The 30 Carbine version [of the Blackhawk] has a different feel, shooting with close to rifle accuracy, probably better than M1 Carbine accuracy.
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