Pretty much how I adjust them until now with .308.  Set it for M80 ball, figuring heavier slugs would have more gas pressure.

Have a 5.56mm now and need to set it up. 
How to determine lowest energy ammo is a mystery without a chrono and a variety of ammo.  Is there some reference for commonly available stuff?

Watch alot of youtube. 223 usually has lower velocity than 556 so you may want to use that? Unless you only have 556.

From what ive gathered as I have been studying this for years. Fed xm193 bulk, pmc 223, aguila 223 , and ppu 223 have a less than stellar fps vs other brands in 16 inch barrel configs . American eagle, norma tac,  black hills, hornady (brown box) have the "higher fps"

B.u.f.f. man range on youtube does a great time chronographing all brands of ammo. And he uses multiple length barrels so you can see the difference. Sometimes too long of a barrel decreases the fps. Lol

if you like your gas block you can keep your gas block

if you like your gas block you can keep your gas block

only for your AR14 - Sleepy Joe

Usually I just throw in a sprinco “hot white” buffer spring and a H1 or H2 buffer. I don’t really see the need for adjustable gas blocks especially in this state that doesn’t allow suppressors into legality.

Usually I just throw in a sprinco “hot white” buffer spring and a H1 or H2 buffer. I don’t really see the need for adjustable gas blocks especially in this state that doesn’t allow suppressors into legality.

H1 or H2 buffers?

Sounds like you only shoot the mouse gun cartridge. 
Build a .308 and it is a different world.

Really for any AR, build your stuff with the right parts and you won’t really need an adjustable gas block. It’s all more or less a band aid for industry inconsistencies.