The internal finish of the gun, which impacts how well the halves of the receiver move against each other, how it feels when it locks up, etc.
When you shut a Perazzi, it feels like a Swiss watch. There's really no pressure, just a quiet, smooth click as it closes tight as a bank vault. This perfection is part of what makes the guns last and last, even for Olympic competition, where extensive practice puts hundreds of thousands of rounds through a gun in a relatively short time.
A production Beretta feels good, but there's a bit more force required. It doesn't feel like it closes itself, like a Perazzi. But it's smooth, and you can tell that the machining is very well done. They also last, and they feel good, but they're not hand-made like Perazzis and you know it when you compare them side by side. (Beretta also makes some very high-end competition guns that are in a Perazzi's price range -- I'm talking about the more common guns like the 682/6/7 guns that you will likely come across in retail stores and at regular ranges.)
A Stoeger feels rougher, and shutting it takes a bit more effort. You can tell it's made to be "good enough", but not perfect.
Again, IME the Stoegers will last, especially doing what you want to do with it.
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