This is basically the same question asked in a 2009 posting. But with one major difference, instead of the targeting the M1 Carbine, I'm looking at the Blackhawk. This should provide much greater margins for safety.
This stems from a conversation I had with my Nevada gunsmith (for the purposes of this conversation let's call him, Nevada Smith) who's smithing my .30 Carbine Blackhawk. We were discussing the .30 Carbine cartridge and, well, all rimless autoloader cartridges. The point he made was interesting.
Without the ability to roll crimp these cartridges, because they're headspaced on the case mouth, you're really not getting all you can from these cartridges. Simply put, the harder it is for a bullet to escape the case, the more tightly held the bullet is, the more completely the powder will burn in the chamber and barrel. And the higher the pressure level will get.
Now here's the interesting point: Nevada Smith stated that the best way to compensate for this is to load heavier bullets. Hence the premise of my question: Are 150 gr. cast bullets practical for a .30 Carbine Blackhawk?
BTW, Buffalo Bore offers a 125 gr. hard cast round for the .30 Carbine.