For Triple Seven (so named because) 100 grains volume equals 77.7 grns by weight . Blackhorn’s Load Table says 100 gr of BH209 by volume equals 70grs by weight.
So the marketing dept at Blackhorn figured that you can get the same number of 100 gr loads (by volume) from 10oz BH209 as you get from 16 oz of T7…so they packaged it like that then charged 50% more because people are well, in general, gullible. :)