If you do choose to use 10mm with the 220gr ammo, be sure to take it to the range first. I know some guns (cough glock 20) will not stabailize them with the factory barrel.
As far as the question gues, I would take the 10mm every time. I'n order to really get the potential out of .357 you really need a decent legnth barrel. I for one am not interested in carrying around or trying to unholster quickly anthing larger then a 3" barrel revolver.
If you would like to see some tests comparing the two rounds in ballistic gel go on youtube and search for TNoutdoors9. The results are quite interesting.
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