I run JP springs. Either the polished or Silent Capture Spring.
https://www.jprifles.com/1.4.7.2_os.php
I have also had good results with the Spikes Tungsten buffer but I run suppressors on all my rigs.
https://www.joeboboutfitters.com/Spikes_Tactical_T2_Heavy_Buffer_p/sp-sla00t2.htm
You might consider an adjustable gas block. It allows you another way to fine tune the rig and it will be set up for a suppressor if you decide to add one later.
http://slrrifleworks.com/index.php?route=product/product&product_id=124
