Does any one here have a 20 var tag made by copper? If so what size bushing are you using for the the 21 firer ball brass or the 17 fire ball brass with the reding s die.
Don't have a Cooper in 20VT, but my 20VT using unturned Remington 221 brass loaded with a Berger 36gr MEF bullet has a loaded neck diameter of .230". I would suggest a .228 bushing if using Rem. 221 brass.