I see the 45-70 hard cast bullet misunderstanding has surfaced again, Mr. Garrett has done nothing but apply information already in existence.
The determining issue of bullet penetration is sectional density, with enough energy to do the job required , and stout bullet construction.
Rifles designed to a specific task were the [size=78%] 6.5 Japanese, 6.5 Swede, 6.5 Carcano, 7mm Mauser, 8mm Mauser, all Military rifles shooting long round nose bullets designed to shoot through trench parapets, or sandbags.[/size]
A 45-70 shooting a long heavy solid bullet will also penetrate quite well given a sectional density in the 300 plus range. Velocity increases energy, or the ability to do work and have a flatter trajectory.
I find it hard to believe a [size=78%]quality solid from Barnes, Woodleigh, or Hornady would be inferior to a cast bullet. A Hornady DGX bullet would work well if sufficient energy is available for the expanding bullet to keep penetrating.[/size]
I shoot a 416 Rigby caliber rifle, the 400 gn , 416 solids I use have a sectional density of 330, 2370 fps, 4900 ft/lb [size=78%]energy.[/size]
[size=78%]I can easily load down to any energy of a 45-70 still using a 400 gn bullet with a sd of 330, supposedly this would give me superior performance.[/size]
[size=78%] A 405 gn 458 has a sectional density of 276 and hardly can reach 2370 fps except in some rifles, certainly not in a lever gun,and should not penetrate better than my 416 when both are shooting 400 gn bullets.
Most big game stopping rifles shoot 500 gn bullets, STOPPING RIFLES are for stopping charges of wounded big game.[/size]
I read the exploits of Mr. Lupo in an article, he shot a Leopard at 9 inches, all of his game was shot very close
I have great respect for his marksmanship and raw courage and dumb luck.
To return to the original question of Grizzly bears, a friend of mine stopped a charging grizzly on two occasions in Alaska, both times he used 10% Capsicum Pepper spray, both bears dropped. A Grizzly's nose is 600 times more sensitive than a dogs, the spray works very well.