typename FTimerDelegate::TUObjectMethodDelegate< UserClass >::FMethodPtr InTimerMethod
jesus this line got my brain steaming trying to figure it out.
It did not help that there is 5 more SetTimer() methods out there so to find how this one should look like was a propper headache.
I still don’t really understand it pretty much completely so if there is someone who will read this and have the patience and knowledge to enlighten me I’d be a very happy broken brain.
but in the end I decided on
GetWorld()->GetTimerManager().SetTimer(DestroyTimerHandle, this, &AProjectile::Timer, DestroyDelay, false);
and AProjectile::Destroy(); and it works wonders at least as far as I can tell - removes the projectiles from the world