jortimer,
you can pick and choose selected loads all you want, when you pick the BEST loads the 10mm slightly bests the 357, It is close enough to call a tie.
You keep quoting loads from Buffalo Bore, when Double Tap beats them in both 357 and 10mm. You are quoting 180 gr loads moving at about the same speeds as Double Taps 200 gr loads.
I've got a chronograph too. My G-20 is shooting DT 200 gr loads faster than your G-20 is shooting BB 180's. DT's 357 loads are hotter than your BB loads too.
"The Glock in 10mm is also becoming quite popular in Alasks for bear defense. With the right loads penetration is right up there with 44 mag.
I make that quote because it is a fact. Many in Alaska are carrying the 10mm over 44 mag now for several reasons. The 44 has more enegy and slightly better penetraton, but neither 44, 357, or 10mm are rifle rounds. All come up short. Evidence in actual shootings show there is no real difference. All 3 work about the same in defensive shootings. In a handgun only the monster guns such as 454, 460 and 500 S&W are proving to actually do any better. And not everyone wants to carry that much handgun around. I'd personally carry a rifle if I felt I needed a handgun that big.
The G-20 is gaining in popularity for several reasons. It obvioulsy holds almost 3X as many rounds. Since all the reasonably sized carry guns have proven to be about equal in performance, there is no reason to be limited to 6 rounds.
They are also smaller and more compact. A G-20 is almost exactly the same weight and overall length as a 5 shot 3" Ruger SP-101. Alaskans getting into and out of small planes find that a good thing.