I've handled and shot a fair number of the Sc/Ti Magnum J's. Yes, the recoil from Magnum loads can be brutal.
I own a pair of M&P 340's, which with their stainless steel cylinders weigh in at less than a regular 15 oz Airweight, but more than an Airlite PD (with titanium cylinder).
I ordered the first one just when they were being released (so it came with the ILS, or "lock"). During the first couple of range sessions I used an assortment of Magnum loads, checking for bullet pull. Over a hundred rounds of Magnum ammunition. I let a few of the other instructors try it, and most of them were happy to give the gun back after a cylinder load of Magnum loads.
I typically use +P loads for the bulk of my quals, training & practice nowadays (since it's issued, and I can also buy one brand at a LE distributor), and haven't shot much in the way of Magnum through my M&P 340's after the first few qual sessions. I prefer to use +P's for carry roles, too.
I'm still trying to wear out my first M&P 340.
Oddly enough, although my second M&P 340 is the latest model, made without the ILS, I've found I'm usually carrying my first one (the "lock" model) for daily CCW, and it's seeing the bulk of the normal range duties. Perhaps it's because all the use it's seen at the range has made the trigger become pretty smooth ... and maybe it's also partly because all the scratches, nicks & general wear its accumulated has made it seem familiar and comfortable.
Whatever it is, I'm going to try and run through another case of +P before then end of the year ... but I probably won't be shooting much Magnum through it. Maybe another few cylinder loads. Maybe.
I think the Airlite Magnum J's are pretty much right out there at the very edge of what's endurable for human/revolver interaction, myself.
Of course, there was that one strapping young man I met at a S&W revolver armorer class one time, who told me he'd fired hundreds of Magnum loads through his 5-shot PD (can't remember whether it was a 340 or 360), and he was eagerly planning to order a M&P 340 and use nothing but Magnum's in it. Okay. Good for him. (Better him than me).
I've got my Ruger SP-101 DAO for a steady diet of Magnum loads.
