btw, Longshot will kick like a fothermucking mule if you load it at the max spec (which i do, cuz i'm insane), yet the low-ish pressure won't abuse your chamber too much. if you wanna start off easy, use the opposite end of the spectrum, like Hodg Clays. nice low charge, a very manageable recoil, and quite clean burning.
btw, make sure you have a caliper (cheap digital is fine) and a bullet puller hammer - JUUUUST in case you mess up a round or two.