Low tech farting around comparing capacities using AA-2230 to the bottom of the necks, the 22x47 has a grain and a half advantage over a 22-250 in fired brass. Likely more if I'd only gone to the shoulder.
The 22-250 has around .050" total case taper with a 28* shoulder, the 47 has .013 taper and a 30* shoulder angle. Damn close to a factory "Improved" case
