Yahsoos crap, if they ain't coming out the barrel, they ain't even sonic! How the heck do you chrony those? Get a lot closer, huh?
When you go under minimum loads for jacketed, it won't be long until a rod and a mallet are part of your kit. Get a manual, follow he guidelines. Problem solved.
The camp nine is a blowback design. You hit the pressure level, the breech opens, the bullet stops.