I did this a while back and i think it works:
ProjectileMovement->OnProjectileStop.AddDynamic(this, &AProjectile::OnStop);
void AProjectile::OnStop(const FHitResult& Hit)
{
ProjectileMovement->SetUpdatedComponent(CollisionComp);
ProjectileMovement->Velocity = FVector(1000.0f, 0.0f, 0.0f);
ProjectileMovement->UpdateComponentVelocity();
}