Yay! Apparently, Starline Brass has also seen the light and is making brass for the 450b:
Read more: https://www.ammoland.com/2017/04/starli ... z4fXmsZKTX
SEDALIA, Mont. -(Ammoland.com)- Starline Brass will be featuring several new popular rifle calibers at the 2017 NRA Annual Meetings in Atlanta.
To accompany their full line of superior quality brass, Starline will soon be adding .243 Win, .223 Rem, 6.5 Creedmoor (small and large primer pockets), .300 Blackout, .450 Bushmaster, 7mm-08 and .260 Rem.
Stay tuned to www.starlinebrass.com to order these new calibers factory direct online as they become available.
Starline has already launched several other new rifle calibers including .308 Win, .358 Win, .338 Federal and .444 Marlin. All are available to order now on their website.