300BLK Upper build advice? please.

[20X11]

300 BLK can be finicky about is gas/bcg/buffer combinations. In 16 inch carbine gas, you will never have an over-gassed situation...making an adjustable gas block less than worthless. A properly tuned pistol length gas system will not need an adjustable block either. Some use JP stuff, but a properly lubed standard buffer system is really all you should need. Spend the extra money on ammo. Low mass bcg makes tuning system harder. Stick with standard or FA bcg.

Finally, Billet is a personal choice...usually for a nice fit between upper and lower. 300 BLK will never need any additional strength provided by billet. Forged is fine and less expensive.