[m21sniper]

It's all within SAAMI recommendations supposedly. In fact a lot of it is not even rated +P. (That tremendously performing .45 ACP round is just standard pressure)

There is a lot of information regarding pressure levels in my follow up posts on this thread. Double Tap gets it's tremendous velocities by maintaining a higher average pressure, as opposed to a single massive peak pressure.

It's interesting to me that the 9mm loading is virtually identical in performance to the .357 sig, .40S&W and .357 magnum loadings. This further reinforces my oft stated belief that the 9mm is the best self defense round available, all things considered.

The .45 does offer tremendous performance, but you have half as many rounds as a typical "wonder nine", and typically, heavier recoil.