Do Chapters still create First Born Marines? The answer to this is going to be based on a number of factors.
Practically, what can the Chapter support? If you have the materials (armor, weapons, transport, etc.) to support 1/4 Primaris, and 3/4 FB
you might create new Marines accordingly. Combat doctrine will also figure in this equation as well.
Some chapters of a more bellicose nature might value the new physical prowess of the Primaris above all else. They will build their Marines accordingly.
Some chapters might go all in and not only build all new Primaris, but subject the entire chapter to the Calgarian Rites.
Guy Haley, in his Primaris novels, 'Dark Imperium' and 'Devastation of Baal' paint a decent picture on how the Unnumbered Sons are parceled out the bolster established chapters as well as create new ones. With the exception of a few First Founding chapters receiving 500 Primaris, the upper limit seems to be approximately 100 Primaris.
Edited by Brother Lunkhead, 15 April 2020 - 03:14 PM.