I have some short jackets I think are for a 44 cal... but I do not cast bullets and would like info about them. If anyone does this.
I have some half cups/short cups that were my fathers. one set of them is in a hornady box labeled 44 mag half cups... the others are loose. I do not cast so I am not for sure of their usefulness. Dad said he used them years ago to try on lead bullets (learned from PO Ackley info) so they did not melt in the barrel and he didn't like doing it after trying it out. So he set them aside. The cups are as so:
There are 289 of the cups which measure outside @ .245 They are .389 tall and inside diameter is .388.
The other set of half cups measure an outside diameter at .249 and are .303 tall and inside measure is .390 and there are 659 of them in a hornady box. Original count was 500... he must have combined what was left of two boxes.
Hopefully that gives enough info for those who might know what they are and whether or not they are of use....

I strongly suspect either your measurements are honked up or you have typos. They do not match either standard .44 cal or .38 caliber bullet diameters.

Half-jacket bullets fell out of favor because they either lead the bore horribly or have been known to stick in the bore if not loaded to full velocities.

Got it... .425 and .429 with wall thickness measure of .018. They did fall out of favor but they are still being used by some people swaging.

As far as I know, they were never used on cast bullets, unless the cast bullet was used instead of lead wire for swaging. The end product should have been like the old Speer half jackets with no lube grooves.