Originally Posted by MontanaMan
A 16" mid-length gas barrel should have a gas port size of .078-.081", as a reference point.

Buy a barrel from a reputable source & likely you will be OK with a standard, non-adjustable gas block & either a Sprinco Blue or a JP spring..............both are very slightly enhanced power rated springs.

Here's a source for both those springs:

No Kick Spring & Buffers

And likely an H(1) buffer.

Every mid-length barrel that I have with a non-adjustable GB runs that setup just fine with ammo from standard 223 to 5.56 Nato.

Worst case, you conceivably might need an H2 weight buffer, highly doubtful you would ever need a carbine weight buffer w/o an adjustable GB.

I strongly suggest that you buy a chrome lined barrel from BCM, FN or Criterion................all 3 are very consistent on gassing & more than accurate enough for your use. BCM has a standard grade & a hammer forged grade.............both shoot fine, IME.

Good Luck.

MM


Lots of solid advise here.

For our ARs we run the stronger green Sprinco rifle spring and need 0.083 port on a mid gas 16 inch for all weather reliability.

I think the pendulum has swung a bit to under gassed for some brands and high altitude/ cold weather/dirty guns need enough gas to drive a strong feed spring.

OP seems a bit worried about overgassed but keep in mind undergassed means the AR won't function.

A bit overgassed means gun runs even when dirty/cold/high altitude.

John Burns

I have all the sources.
They can't stop the signal.