The bunch I worked for years ago mandated and supplied +P+ in 115 and 124 grain variants for those of us who preferred to carry personally owned 9mm Glocks and Sigs. I have personally shot several thousand of them thru a Gen 1 G17 and Gen 2 19 with no problems and not even any perceived acceleration of wear. That was back in the day when the .40 was in its infancy and everyone was beginning to marvel its performance. With that agency, however, of the officer involved shootings with 9mm +P+ loads, I know of none that required more than one round to stop the attack. When I changed employers, I still carried a 9, but this time 147 grain Hydra Shoks. I didn't notice any difference in perceived recoil from the same pistols. One local agency I currently work with has issued the Winchester 127 for years and have been happy with its performance; first in third gen S&Ws, and then in Gen 3 & 4 Glocks. The third gen Smiths had their share of problems, I'm told, but ammo did not seem to be culprit. I had talked to an old fed who had been around since the original 110 grain +P+ Treasure Load and had carried a variety of J and K frames with that round. He said that the only issues he'd seen were the smaller guns suffering increased wear. An internal part might break once in a while, or the timing might go out of whack, but the guns never Ka-boomed. The M&P 9s are pretty robust, so I would not be concerned with catastrophic failure caused by a properly loaded commercial bullet. It might wear out the springs faster. I don't know that I'd necessarily use it in a Shield, but aside from a maybe slightly more unpleasant recoil, it would likely accelerate wear &a tear. That said, I would not shoot it in some cheap, off-brand ***. For what it's worth, I still see some Federal aHydra Shok 38 Special 147 +P+ in J frames and have fired a fair share of it myself. Original FBI specs clocked the velocity at 950 fps, not really any more potent than their earlier FBI 158 LSWHP. While neither is pleasant to shoot thru a J, they aren't so brutal as to cause structural failure unless quality control on either product, bullet or gun was absent on the day of manufacture.
