Just be careful...there are many vest that just scream "he's packing!" Sometimes it's good to keep it more discreet.me, I carry one or the tother depending on what I am wearing. .380 or the .45. Although I am buying a vest that will conceal both. If you can try to shoot as many different pistols as you can.
Or at least see if you have friends' who might allow you to see how their pistols fit your grip. (alright you bubblegummers, get yer minds out of the gutter)
A 9mm and 357. Yeah i carry two, have for the last 6 months-year
In the next few months I may switch over to a .40 or .45 and replace the 9.