My bad, but even so if land owner, shoot syndicate of whatever stipulates factory ammo, then you should use it. Things like land owners insurance will be driving such decisions.
Yes home loaded ammo may be more accurate etc, but if you have a rifle that cannot shoot factory ammo well enough to shoot deer there is something fundamentally wrong with the rifle.
And over the years there too many accidents caused by faulty home loaded ammo - especially if used in another rifle for which it wasn’t developed. Chamber a round which has its bullet seated long into another rifle you will get a huge pressure spike.
Fundamentally if a landowner, or guide, or shoot organiser stipulates particular type of ammo, moderator etc you have a simple choice - either comply, or use an estate rifle or go elsewhere.