Ideas on making a core die

[wywindsor]

I have a blank 7/8'' die. A mill and lathe. I need a core die for a .22 spent case setup I bought. So I'm thinking .1875 roughly maybe somewhat larger as the derimmed cases are .203. So where to start. Drill hole size followed by a reamer of which size. And how many steps to the final reamer size. Next I assume is to polish it. How and with what. Any help on the how's and what greatly appreciated. I have a Corbins S press.


Thanks

[contendernut]

.190 and .191 are my sizes of squirt dies for 224

[deltaenterprizes]

I use .187” wire for cores so a little bit bigger and still a readily available
reamer size.
The die may grow slightly when you polish the inside.
The punch should be .0005-.001 smaller than the inside diameter of the die.
You can polish the inside with wet or dry sand paper and oil going progressively finer all the way up to 2000 grit.

[midnight]

I would drill and ream my hole about .001 too small, say .189 and then using an expandable brass barrel lap, lap it up to .190 using progressively finer clover lapping compound, 400 to at least 1200 the finer the better.

Bob