16 Inch Middy Gas Port Diameter- What Works?

[MistWolf]

Does anyone know what gas port size Colt is using on the 6920-CCU? Does anyone have first hand experience with the CCU? Is it over gassed?

To those who have tinkered with gas port sizes on 16 inch middies, what size have you settled on for good function without being overgassed without a suppressor? Is a .081" gas port too large to run without an adjustable gas block assuming a quality carbine spring and an H or H2 buffer is used?

For now, please limit the discussion to a carbine RE, spring and buffer to establish a baseline

[tom12.7]

I do not know the porting for that combination. I am away from my notes and pretty busy right now, so sorry if this sounds vague. A gas port size of .081" conventional mid gassed 16" 5.56 AR barrel is pretty heavily gassed for most uses. Adding a possible can to that makes that worse. Selected ammunition types and temperature ranges could help narrow down a more preferable port size that envelopes the characteristics of the selected can using the conventional carbine action with dedicated 3.0-5.4 oz buffers for uses.

[MistWolf]

The rifle in question will not be used with a suppressor due to jurisdictional restrictions

[markm]

.076 is about right. .080 works good for 14.5 middy with no can.

[tom12.7]

That can get closer, but I'm still away from my notes on this.

[Clint]

.076 is the largest I like to see.

Smaller than that can work well, provided quality components are used and the gas system has minimal leaks.

[MQ105]

I have a 16" BCM CHF mid-length and I am running a homemade .0635" gas block port. A2 flash hider, carbine RE, H2 buffer, Tubbs carbine flat spring. It runs Wolf Gold and every 5.56 load I've tried when dirty and dry.

[tommyrott]

Had a Rainier select 16" midlength using a micromoa govanah with a .070 plate and an A5 h2 ran quite smooth with handloads of 24.5 of tac + 55 gr hornady SP

[Iraqgunz]

.076 is a good number that will run in a variety of conditions and with various types of ammo.

[vicious_cb]

Any middy,14.5 or 16 that has a gas port diameter where the first non-zero number starts with 8 is designed to run with shitty ammo.