T2K, While I have never had any 2Z ammo to chronograph, I have read that the 2Z ammo is hotter than average 9MM. I have used and chronograped a fair amount of the warmer 9MM, such as +P, +P+, IMI Carbine ball, machinegun ammo, etc, but never in the P-38. Like GCBurner, the slide on my WWII vintage P-38 cracked. My slide cracked in the area where the locking block locks into the slide. This is the same area where some of the Beretta 92 slides,which use the P-38 type locking system, were reported to have cracked. I was not using any warm ammo in my P-38. The later P-4 version of the P-38 has a higher sidewall on the slide, which reinforces the locking area. I suspect this change was made for a reason.
I like the P-38s, but definitely I would not fire anything hotter than regular SAAMI spec. ammo in them...ymmv