I am ready to pull the trigger on a Sig P239 this week. This will be the smallest footprint autoloader that I own, and the only single stack I would own other than a 1911. I have decided to purchase the GEN 2 SAS version of the 239, and use this for those hot Virginia days, or any time concealment is more difficult. My quandary is deciding what caliber to get. I own a 226 in 9mm, a 226 in 357Sig(with a 40SW barrel, and a 229 in 357Sig(with a 40SW barrel). I like the idea of the interchangeble barrels obviously, but I understand the single stack 239 will cost more to interchange as the magazines are not interchangeable. So in addition to the cost of another barrel, I would need to buy additional dedicated mags as well. Below are some considerations I have tossed around. 1 Round count between the calibers is not a huge issue (without using an obtrusive extension the round count is 7-8) 2 Because the round count is about half of the double stack version of the same caliber, an effective caliber is more important possibly. 3 I have large hands and the 239 is the smallest framed gun that I can comfortably grip. I have handled and shot Smith's Shield, Beretta's Nano, and Springfields XDS...and the winner is the 239. 4 With my larger framed autos I can comfortably shoot all 3 calibers, and although there is some differences in recoil, there are no real isssues with the recoil and getting back on target for follow up shots. That said, even though the 239 is steel frame and heavier than some pistols of similar size, I would take recoil and stability more in consideration with this frame than on my larger framed pistols. 5 I have only shot the 239 in 9mm and 40SW, but I frequently shoot the 357Sig (and carry that round for concealed carry with the 229). 6 With the 226s shooting all three calibers side by side in the same session, the tightest groupings for me are with the 357Sig. Not huge diffeences in groupings, but slightly better. 7 Ammo costs are highest, availability.variety lowest for the 357Sig; while lowest cost/best availability is for the 9mm ammo. 40SW somewhere in between. Any other considerations I am missing? Any thoughts or experiences of the forum members to share that might help me out? Thanks! And sorry for the long post.