• There are all sorts of questions about factory ammo which are answered in the Stickie at the top of this forum entitled: DIRECTORY of Ammo Buying Information
• I note that you did not mention the brands of your +P ammo. There are some legitimate +P brands (Federal, Speer, Remington, etc) and bullet weights made for law enforcement. However, a great number of +P offerings for the general public are made by "personal defense" specialist who only make that one type of ammo. They are 'highly acclaimed' in their own YouTube video and no where else. They pretend to make a better ammo based on the fact that they use a proprietary bullet. These bullets always have strange ogive shapes and a menacing appearance.
There are 2 problems with this type specialty ammo:
1. FIT
The big problem with specialty bullets, an issue well known to every reloader, is that not all bullets fit the CZ chamber. The CZ has a shorter freebore and uses a fully supported chamber, both of which severely limit the design of ammunition used in CZ pistols. Amateurs falsely assume that there is a standard 9mm Luger round 'size and shape', and thus, all 9mm ammo fits all 9mm handguns. This is a false assumption. It doesn't fit unless you've done 'plunk and spin' tests on several rounds in your CZ barrel. Furthermore, we also know that CZ chambers are not standardized across the line up. The Shadow chamber is not like the PCR chamber, which is not like the P07 chamber.
2. FEED
In order to be successfully used, SD ammo must be known to feed reliably in your firearm. It may feed perfectly in the Glock or S&W firearm in their video, but that doesn't mean it will do so in your CZ. You'd need to run several boxes of this ammo through several different mags to reach this conclusion. Typically the price or availability of said specialty ammo precludes this type testing.
The Bottom Line is this.... any questions about chamber pressure take a distant third place seat to the questions of Fit and Feed.
Just my 2 cents.