I own a 340PD.

The issue with light magnum loads is the projectile jumping forward of the not very sturdy crimp. I has this happen twice on two different aluminum and scandium J-frames.

A scandium frame with a titanium cylinder is especially prone to this. It will lock up the revolver, a bad thing to happen during an urgent need.

I also have a pair of 342's and a 242. I make a point of only shooting wadcutters in them.