Opinions vary widely on the topic of steel cased ammunition. Everything from, "it's the greatest thing since sliced bread," to, "you might as well start saving up for a new rifle, because yours is doomed!"
So, will steel cased ammo destroy, or at the very least shorten the life of your favorite rifle? Well, as is the case with most myths, in general, probably not, but it depends. I know, I know...after reading that, you're thinking to yourself, "What kind of answer is that?" Honestly, it's the kind of answer you should expect with firearms. Just as there is no "best" anything that applies to all firearms, there's no universal "worst," either. You take each firearm design and function individually, just as you take each person or car in your life. They're all different shapes and designs, they handle differently, respond to conditions differently, and some are in better condition than others.
The video at the following link below, produced by Brownells, featuring there staff gunsmiths Steve and Caleb, discusses the topic of steel cased ammo and puts to rest many of the misconceptions surrounding this controversial subject.
Smyth Busters: Will Steel Cased Ammo Damage My Gun?
To sum up, generalities (or a "one size fits all" approach) won't work...not with ammo, not with scopes, not with triggers. Your firearm is a tool; nothing more, nothing less. Some have a specific function (i.e. target shooting), and some are general purpose. But whatever you use your firearm for, the ammunition you use should be chosen to fit that purpose. You wouldn't use a bit designed to drill a 1/2-inch hole in plywood to drill a 1/2-inch hole in concrete, would you? (Okay...I probably offended some people with that question.) The answer is NO. Do some research and determine the kind of ammunition that is best suited to what you're trying to do with your firearm. There are a HOST of old axioms that apply here: "Garbage in, garbage out"; "If you want it bad, then you'll get it bad"; "Use the proper tool for the job." But, above all else, safe operation of the firearm should be the final determining factor.