Jyezhan
+P ammo is more powerful. I have compared it with standard SD ammo and find the +P has approx. 40% higher fps and 40% higher ft. lbs of energy. The +P+ is way overpowered and could be dangerous. Smith says any ammunition that meets SAMMI specs is ok to use. All reputable ammo manufacturers make their ammo to those SAMMI specs, including the +P. However the +P+ is usually over SAMMI specs, meaning too powerful. Smith says the use of +P ammo will cause excessive wear. That is true if you were to shoot many hundreds of +P rounds. +P does produce a faster and harder recoil, and this is what causes the excess wear. When the slide reaches the end of the recoil, that jarring stop is what causes the stress and extra wear to the rails and slide stop inside the frame, and frame flex. But since most SD ammo costs in excess of a dollar a round, not too many of us are going to shoot excessive rounds of this ammo. I personally shoot around 4 rounds of each caliber, each trip to the range, just to keep the felt recoil and flip in my memory bank.
The blown out casing that was shown in the OP, was a result of the barrel not supporting the casing. I have shot lots of +P through my guns and have not had one blowout, as shown. It was a defective barrel machining. Using standard target ammo, the ft. pounds of energy are usually around the low 325, and the OP said that this low pressure ammo did not blow out the casing, even though fired through the same barrel.
Bob
