I'd go with the 357 since with the right load it is fine for deer but it is a very cheap and fun plinker with the 38spc. Plinking with slugs, even if you load your own, isn't really that cheap and not a lot of fun as even a 20 ga will get to you after a couple of dozen rounds. For about $25 and a little bit of your time you can ream a 357 Mag to 357 Max and get more punch for Bambi, however the 357 Max will require you to get into reloading. The Max will still shoot the 38 plinker loads so the kids can shoot it when they are too small for a 20 ga.
Why be difficult, when with a little extra effort you can be impossible?
Wife's Handis; 300 BLKOUT
MINE: 270W, 308x444, 44 Bodeen Belted Magnum PI (Profino Improved), 444M shorty, 444M, 445 SuperMag Shikari, 45 ACP shorty, 45 Cal Smokeless MZ, 50cal 26" SS Sidekick, 50 cal 24" Huntsman, 50 cal 26" Huntsman, 50 cal 26" Sidekick, 50-70 Govt Shikari, Tracker II 20 ga shorty, 20 ga VR Pardner, 12ga VR NWTF, 12ga Tracker II shorty WITHOUT scope, 10 ga Pardner Smoothbore slug gun, 10ga Pardner Turkey & 24ga Profino Custom rifled slug gun.
Active Trader until: July 25, 2013