Well, OK Old Griz, if you're a wheelgunner then get the 638, period. I don't know how many rounds the P3AT carries but I know you are limited to 5 with the 638. However, 5 rounds of 200 gn swc over 3.8 of WW231 is exactly what I carry in my M38. I have a 380 - love it, but prefer to carry the 38. I feel the 38 Spl has a greater capability range than the 380.
TMANN said he ahs yet to fire defensive rounds through his P3AT - 380 ball is about the best defensive round you can get for that caliber - better penetration than any of the hollowpoints. However, that being said, a 200 gn 38 caliber swc will leave'm leakin' on both sides, if they are still standing. HTH. Mikey.