Lead is lead, and hard cast ain't...

Push a lead slug over 1000-1100 or so and you'll have more skid-marks than my 4yr old's underoos. Hard cast can run over 3000fps without leading. It's just a much more critical balancing act to make it happen. Gas Checked lead bullets are another option too. You might note, Buffalo Bore has a few 45colt, 454C, and even 460 S&W loads which run 1300-1900fps with hardcast bullets.

Now, are you going to do all of the spec checking to be sure you have the appropriate BNH and bullet diameter AND be sure to properly lube your bullets to avoid fouling with hardcast? Anyone can smelt some lead and throw bullets together and end up with a reasonably low fouling load under 1000fps, getting there with high velocity hard cast is sometimes a different story.

There are plenty of rules of thumb out there relating hardness to velocity and/or pressure, such as velocity/100 = BNH needed, so a 1300fps load needs 13 BNH, or pressure/1422 = BNH, so a 21,000psi Tier 2 Ruger Only load would need a 14.8, call it a ~15 BNH... The pressure based version is a lot more relevant than the velocity based rule of thumb, but for 45colt, it ends up about the same. A guy doesn't have to work very hard to get wheel weights up to this level for 45colt Tier 1 or 2. Ruger only Tier 3, full 30,000psi, and 44mag need a little antimony to get up to 20BNH, or water drop/oven bake wheel weights to get there.

Gas checks are another option, not a difficult step, but an added expense and extra step.

Both hard cast and gas checked options are available to the reloader as "factory fresh" options, if casting your own isn't of interest. Personally, I'd rather spend time shooting than casting these days, so I'm happy to pay for my bullets.

Guys shoot hardcast in rounds like 454C, 475L, 480R, 44mag, etc over 1100fps all of the time, 45colt included. It's more complicated than running soft lead SWC's in 38spcl, but it's not rocket science.