I have that very gun, the 638 Centennial Airweight. I bought it just as they were releasing the Titanium and Skandium framed models. I don't reload for it, too much available for too little cost to bother...especially for self defense ammo. I use that very Hydra-Shok ammo you speak of and it shoots well, specifically the +P's since the gun is rated for +P ammunition which gets you danged near a .357 mag velocity. More than enough out of a tiny gun.
You won't be dissapointed with it. I really like the shrouded hammer feature that the other Airweights don't offer.
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