Posting this here per someones request from a different topic.
I recently purchased 2000 aluminum gas checks and had major seating issues until i figured out they had an ID of 0.208" and my 223 bullets had a shank size of 0.216"
Came up with this makeshift expander to resize them quickly and they now work perfect.
It ain't pretty, but it works fast.
Here's a quick video:
https://youtu.be/KwlHUVSizOw.
If you get a double in the hole, or one pops in upside down, just pop of the white plastic part and poke it out.
The hole has to be small enough to center the check below the expander rod, but not to small that the check gets stuck. I drilled a tapered hole with a stepless drill bit from harbor freight.
The plastic is just scraps of PVC and acrylic i glued together with universal PVC pipe glue.