Friend's cow aside, terminal bullet performance has got to be the most neglected area of study in hunting. And some of the bullet/ammo makers are culprits. Marketing a bullet as fully effective on any size game, at any impact velocity between 20 fps to 5,000 fps ( I exaggerate, but not by much) is an issue as the market shifts to encourage longer and longer shots. The fact is that a highly effective bullet at 50 yards is almost never going to be effective at 500 yards and vice versa. And it's not as simple as velocity vs. mass. Each design has it's own sweet spots and its limitations. Bore diameter alters considerations drastically. I'm not the expert. Nathan Foster, who has contributed articles to this site, has done more study in this area than anyone I'm aware of and is an unbelievable resource of knowledge and experience. But I continue to be concerned by some manufacturers' willingness to use unrealistic expectations in their marketing. If I see one more bullet design pushed as the next greatest thing with a picture of a gel block..... As shooters and hunters we've got to grow a culture of careful study, analysis, and dialogue among ourselves that includes terminal bullet performance and refuses to treat magazine and internet ads as gospel.
Now, back to the friends' cow. Do you know the barrel length of the rifle? If you know barrel length and if the published velocity of the load that was being used is to be trusted, and we assume that the published velocity was based on a standard 24" barrel (or even if it was based on a different barrel length), then the impact velocity should be something you can calculate. You've got one of two things: an impact velocity number that you know that bullet needs to stay above, or reason to call the manufacturer about a possible flawed batch of bullets. Every bullet on the market will pinhole if it strikes slow enough. Were the exit wounds pinholes, expanded holes, or just fragment exits? The type of exit wound drastically alters the analysis. I doubt Hornady expects this bullet fail at 50 yards on a large bodied animal. But I also doubt Hornady expected bullets sold in America to be used to make chest cavity shots on bovines. There are a lot of variables. Again, Foster is the best resource I'm aware of. His site is
www.ballisticstudies.com and the Knowledgebase section has a library of field study based information on a ton of chamberings and the available bullets for them, including .45-70. The articles he published on this site on game killing fundamentals are also important reading and applicable to your situation.
