Im curious as to what makes the Blackhawk cylinder too short?
The bullet nose should be flush with the cylinder face in this instance.
In either of my Blackhawks, a 50th Anniversary model (a flattop) and a Lipsey's Flattop, seating a 358429 into full length 357 Magnum brass crimped into the bullet's crimp groove produces a cartridge overall length which is just a hair too long for the cylinder, and will hang up as it rotates into battery.
I think it has something to do with a shorter cylinder on the Flattop models?