The 22 Nosler is the same length case as the 223; unmodified, the sleekest pill is probably going to be the 75 BTHP Hornady in an AR.
The SPC mags might allow a little longer seat, as do specialty/modified mags to shoot the tipped secant ogive models.
Nosler was also hedging bets that the cartridge could be chambered in the more common .378 boltface platforms.
