Chris,
Lots of things affect the strength of steel. What metals are used, the heat treatment, and how much steel there is makes all the difference. Ruger SA revolvers are larger than the Colts and clones, and that's one reason they are stronger. Also, whatever Ruger does with the steel they use in their guns, they've got it down pat.
When I was looking to buy a SA .45 Colt revolver, I went to a local gunshop to look at a few. Now, I don't have to attend an SASS shoot to dress like a cowboy 'cause that's the way I dress every day...and always have. Well, the salesman says to me, "Well, you LOOK like a cowboy. You might as well buy you a gun so you can feel like a REAL one." (now I'm thinking "what an assinine &*%$#@$%!) I'd say his sales approach needed a little help, becaues I already owned more guns than I care to count. The salesman then tried the same thing with me that happened to you: he tried to convince me that the Uberti was every bit as strong as the Ruger. When I mentioned that I intended to use heavy handloads, he told me it was more than strong enough to shoot anything the Ruger would handle.
Now, another thing he didn't know was that I've owned and shot guns all of my life, his boss (the owner of the store) was an aquaintance of mine, and I used to work at that same gunshop back in the '80's when it was under different ownership. I KNEW what he was telling me was a lie, but I just acted the part of the stupid cowboy that maybe got kicked in the head a couple too many times as a kid and said things like "Really? WOW, I didn't know that!"
I never did tell him what a silly fool he had made of himself, but I think maybe his boss did. I haven't seen him there in a long, long time. It serves him right, too.
A day or so later I bought a Vaquero from a shop a few blocks away, and I've spent a lot of money at that shop since then. I don't deal with folks who insult me a feed me BS, and the other fella's treated me more than fair.
~Rat