It's because the chamber is a spec 6BR Norma chamber. 6 BR Norma factory ammo is loaded with 107 gr bullets. They won't put a shorter freebore in a chamber than what factory ammo needs. Have you ever seen any factory 6 BR loaded with 70 gr bullets?

Don't lose any sleep, many of the long throated chambers still shoot quite well with a good amount of "jump". Seat them back where you feel they have enough support and try it.