I shoot +P 125gr from my 637 pretty regularly, and while they are spicy it's not too bad. That said, they were 125gr at ~825fps from a snubbie, so they are nowhere close to BB levels.
As I posted in Hoptob's thread, if you google
"Four High-Performance .38 Special Handloads" our own bmcgilvray posted a great thread on another forum that has 2400 and 4756 loads that emulate the BB load.