In Imperial Armour 9
This suggests the Tiger Claws had some spare gene seed, but where would Huron have got the gene seed to produce 2000 over warriors? How could he/and other chapters produce new gene seed? I also know new gene seed is produced on Terra but Huron would not have used that as he wanted to keep his plans secret from the High Council.
So how could he/or other chapters produce new gene seed apart from their dead brethren?