Finn used a 375 H&H and 458 win mag to take the big 5 and he certainly had access to the 458 lott even though it was a wildcat cartridge until 2002. (When Finn died in 2000 after a long battle with cancer, he passed on to his son Harald his .375 H&H and to his other son Erik, his .458 win mag. He left these two rifles as a legacy to pass on to the children and grandchildren.) While other gun writers were condemning one cartridge or another as totally useless Finn would objectively test them against measurable means. So why didn't Finn switch to the lott from the win mag if the lott is a better cartridge? Due to the lott not being a commercially available cartridge at the time? I wouldn't think that would be the sole criteria.
