Here's a fired .45 ACP case- fired primer left in. Beside it are 2 .440" Hornady swaged round pure lead balls for a muzzleloading rifle. I pushed both balls into the case, then used my bench vice to lightly push the top one in until it stopped, making sure both were bottomed in the case.
The resulting "bullet" weighs 345gr. and measures 470" (I sized it originally in my .45 ACP Lyman carbide die. If a pair of .445" balls are used instead of the .440", the resulting 'bullet's weight will be approximately 350gr.- at least that is what I got.

After seating the balls, either .440" or .445", I ran them into the .45ACP die again just to get rid of any bulging.

A .45 calibre bullet of 250gr. or more, could be seated in the case and a .45auto crimp die could be used for the final crimp, of course - either a strong taper crimp or roll crimp, whichever is desired.

I've shot this type of projectile in several guns - .358's are made from .30 MI Carbine brass, .375's from .223 brass and .458's are made from .303 Brit (rim turned off) and .35 Remington brass.

All of these 'experiments' have shot into 2" or less at 100 meters - usually 1 1/4" to 1.5".

Here-to-for, I've poured the cores from pure or WW alloys, then use a die from my die stock to round or crimp the cores. Checking ctg. base and shoulder diameters can give you an idea what dies will work. it is good to use the shoulders inside the die as the case shoulder angle can give a nice turn-in on the bullet's nose. Annealing the case used for the the bullet helps a lot when sizing them as the become dead soft - no spring-back.