I wouldn't be happy sitting firing that - firstly, their table looks to be in front of the shooters under cover, to their left. Secondly, Firing my 45-70 sitting down was a bad enough experience!!!
Interesting story as to how the .458 Lott came about. Jack Lott was on safari using a .458 Winchester. He shot an African buffalo twice and it still made a good job of squashing Mr Lott!! When he recovered, he decided he would make a more powerful .458 as the Winchester version was described as a commercial success but a ballistics failure!! The figures quoted for a 500 grain bullet are 2,330fps and 6,020 joules.