The Maxim Defense Industries CQB Stock models on this page include the standard 3.3 oz buffer and spring. The models shown from the link you provided include Pistol caliber buffer and spring.
The Maxim Defense Industries CQB Stock Gen 7 for AR-15 is compatible with AR9 platform rifles and PCC's. However, to ensure optimal functionality, you would need to purchase the 7.6oz pistol buffer and spring, which can be found linked below:
https://www.opticsplanet.com/maxim-defense-industries-cqb-buffer-spring-set.html?_iv_code=MDI-RBF-CQBBS-MXM-47569&_iv_weight=7-dot-6-oz
Because your AR is chambered in 300 Blackout and using a suppressor, you will need to use at least an H3 buffer to ensure proper functionality and reliability. You can learn more about the correct buffer weight for your build by reading the How to Guide linked below:
https://www.opticsplanet.com/howto/how-to-select-buffer-tubes.html
This Maxim Defense Industries CQB Stock Gen 7 for AR-15 will not work with the PDX.
The Maxim Defense Industries CQB Stock Gen 7 for AR-15 might work with the POF P415 Edge but I recommend contacting POF to confirm compatibility.
No, the Maxim Defense Industries CQB Stock Gen 7 for AR-15 uses a proprietary buffer tube that is not compatible with A5 buffers, and the stock itself does not fit Mil-spec or commercial tubes.
The Maxim Defense Industries CQB Stock Gen 7 for AR-15 can be used on an AR chambered in different cartridges. If yours is chambered in 45ACP I recommend using the Maxim Defense pistol buffer at the link below.
https://www.opticsplanet.com/maxim-defense-industries-cqb-buffer-spring-set.html?_iv_weight=7-dot-6-oz
Yes, the Maxim Defense Industries CQB Stock Gen 7 for AR-15 will work with a Radian Arms Receiver set.
Yes, the Maxim Defense Industries CQB Stock Gen 7 can be used on an AR9 Rifle. You will most likely want to use the Maxim Defense 9mm CQB Buffer located at the link below.
https://www.opticsplanet.com/maxim-defense-industries-cqb-buffer-spring-set.html?_iv_code=MDI-RBF-CQBBS-MXM-47569
The Maxim Defense Industries CQB Stock Gen 7 for AR-15 is not compatible with AR10's and Maxim Defense does not currently have a model for AR10 platforms.