accuracy issues and ejector swipes-- sounds like its over gassed and need a good adjustable gas block--almost every "factory built" AR is going to have a slightly over sized gas port so that ALL factory ammo will operate the system "reliably". An adjustable gas block can be used to tune the timing, and reduce the gas volume to the BCG--I have multiple gas block settings based on what bullet weight, powder, velocity, suppressed or un-suppressed so that it operates with the proper pressures and extraction.
a band-aid fix can be to use a heavier buffer, but then it may not cycle correctly with some low powered loads
you'll never be able to get the same speeds from your AR as a bolt gun as the AR vents some gas and pressure off while cycling --may times "known" bolt gun loads don't work well in AR semi auto rifles, gotta try to build a load just for that rifle
I don't have a 6.5cm AR, but my 308 always shows best accuracy with varget powder with every bullet I have tried-- its a good burn rate for an AR also
here is the one I recommend:
https://slrrifleworks.com/index.php?route=product/product&path=104&product_id=124
also, AR's take a different style of shooting to shoot them accurately, though your rifle does appear to be pretty heavy so that shot help
if you are reloading, make sure you have enough neck tension, the recoil and feed ramp can drive bullets into the case causing inconsistencies with handloads
where are you empty brass casings ejecting to? straight out to the right, back behind you, or in front of you?