saleen,
Factory ammo. I believe factory stuff is a 405 grain bullet at about 1300 FPS.
Handloading .45/70 rounds is a different story. With suitable handloads in a rifle designed to shoot them, there ain't much, if anything, on the planet than can withstand a "heavy" .45/70 round.
saleen, believe me, I know how handgun aficionados can become loyal to cartridges and impute mythical characteristics to them. I will be honest with you, I do not see much practical use for a .327 Magnum. That doesn't mean it lacks utility. However, I'd rather have 158 grain +P .38 Special ammo than ANYTHING smaller for saving my life. Again, this is just me, I consider the .38 Special as minimum for saving my life. To my way of looking at self-defense, a 1911A1 in .45 ACP is as good as self-defense gets.
The .327 Magnum might be a good trail gun where there is no chance of running into any bear.
Momentum is necessary for penetration, which means heavy bullets. When I've carried a .357 Mag in bear area, it was loaded with 180 grain magnum rounds. When I've carried a 1911A1 in bear area, it was loaded with 230 grain +P ammo. Either of these would be excellent self-defense against bipedal vermin, and in CA, one can never exclude the potential of running in to sketchy dudes. Where we fish, there is no such thing as cellular service. That means I'm on my own when it comes to protecting my kids from any variety of vermin. When we're miles from nowhere in the Eastern Sierra, it is my responsibility to protect my daughter from all animals: beast and human.
I have no ill will toward the .327 Magnum. However, from a practical perspective I believe that there are much better cartridges. I would rather carry .38 Special +P ammo than any .327 Mag ammo. But that's just me. Others might have other opinions. I'm good with that. What's right for me might be all wrong for others.