Sorry to take so long getting back to this thread. Holidays and a ski trip last week have been keeping me from the range.
I shot the 342 a few days after getting it. I fired handloads, charged to the published STARTING LOAD, about 10% off of maximum. These are super easy to shoot in my SP101. I only got through 10 rounds before I packed it up and went home, my hand hurt for an hour.
I don't remember the gun being this hard to shoot.
I didn't get a chance to fire any of my +P, but at this point I'm thinking that it would be a pointless endeavor anyway, since I won't be able to shoot it well.
At this point I'm considering getting some of the 110gr standard pressure stuff for a carry load, since it seems like the 158gr +Ps are not going to be controllable.