I built a 10.5" 5.56 upper with a YHM Turbo T2. Ballistic advantage barrel, Seekins adjustable gas block. PSA M16 bcg.
I have the gas block adjusted so that it cycles reliably with the least amount of gas required. Good 4 o'clock ejection pattern.
However I'm still getting a ton of gas to the face and my brass and magazines are completely filthy.

Is this the nature of the beast or is there anything else that is worth doing?

Someone told me to try an H2 or H3 buffer with a red Springco spring but I'm not sure what difference that would make.

Gasbuster charging handle?

DIY gas buster

This helped a lot on my 10.5"

I've installed these with good results, but the RTV is certainly an easier and far cheaper way to the same goal.

https://www.larue.com/products/gas-buster-charging-handle-with-big-latch/

But the can you are using also has a lot to do with blowback. Some are a lot more egregious than others. I found the OSS line has the least amount of blowback and gas in face issues.

I put Superlative Arms piston kits on two suppressed ARs that I hunt with for this reason. Helps out a ton.

I have had good luck with the PRI gas buster charging handle.

PRI / RTV helps alleviate symptoms.
Keeping the bolt from unlocking longer will send more gas down the actual barrel. Turbo full size is a gassy can.

DI guns are always going to soot the magazines and ammo.

Mike