Every barrel will have it's own "perfect" load. But I think that's because it's a different barrel. Two barrels of the same length might not like the same load. It's a barrel thing, and I don't believe it has much or anything to do with the length.
I have three .45acp handguns. Call me lazy, but I load all of them out of the same bucket of my reloads. If I was a bullseye shooter I might work up a load for each one individually, but I'm not.