I can only speak of the AR. As stated above, the 4uad hop unit is a worthy upgrade. I'm still testing the 4uad bucking myself, so far so good. In my community the go to is now the unicorn 70° bucking. A unicorn barrel is nice to have but not strictly needed and the new nozzle design from the MCX seems to be becoming the gold standard so start looking at how to mod them to fit.
And lastly Waldo dynamics launched a new NPAS that's much better suited for us in the UK.
If anything I'd say watch some explosive enterprise YT vids before doing any mods and stay well clear from some other YouTubers advice on these platforms, they'll side grade or worse downgrade your rifle.