From that article, they need a reality check..

Quote:

A 300-grain, well-constructed bullet moving at about 2,000 fps is 150- to 200-yard bad medicine for just about anything, including bear and moose. It's certainly big enough for elk, and there's not a deer alive that will walk away from a solid hit. The energy of such a combination is 2,400 foot-pounds at the muzzle and, within 100 yards, it doesn't weaken much. That puts it squarely in the territory of the modern .45-70 or .450 Marlin, and it will do anything those rounds will do. The mighty .458 Winchester Magnum only bumps 2,100 fps with the 300-grainers.

The level #1(Trapdoor <28K PSI) 45-70 pumps 300gr slugs out at 1800-2000fps.
Level #2(Marlin Levergun 28K to 40K PSI) 45-70 at 2300-2400+fps.
Level #3(Ruger#1 40K PSI to brass capabilities) 45-70 at 2400-3000fps.

The 450 Marlin pumps them out at 2000-2400fps.

The 458Win pumps 500gr slugs out at 2100+fps. 300gr slugs out at 2400-2500fps or more.