A page from MicroMOA through Internet Archive on 16" rifle length gas. Might help in trouble shooting if you buy one.

16″ Rifle Gas Competition Setup – Adjustable Gas Tuning

We have tested the following configurations to determine optimal port sizes with this barrel using the MicroMOA Govnah for various common competition configurations. All testing was done with little to no lube and in Florida during summer temps. Ammo used was green box Remington Value Pack .223.
** Special Thanks goes out to RCA Rubber City Amory and Boomfab for their assistance in obtaining these results. **

Carbine Stock Configurations, ‘White Sprinco‘ – standard power spring used for all testing except for JPSCS which is using the standard JP captured spring.
1. .082 – Boomfab Titanium Carrier, JPSCS
2. .089 – Full Weight Carrier, JPSCS
3. .089 – BoomFab Titanium Carrier, carbine buffer
4. .093 – Full Weight Carrier, Carbine Buffer
5. .093 – RCA LW Carrier, Young LW Carrier, Carbine buffer
6. .096 – Voodoo LW Carrier, Carbine buffer
7. .096 – BoomFab Titanium Carrier, H buffer
8. .098 – Full weight Carrier, H buffer

Rifle Stock Configurations, standard power rifle spring used with all rifle stock testing
1. .089 Boomfab Titanium Carrier and Rifle buffer
2. .093 RCA LW Carrier, Young LW Carrier and Rifle Buffer
3. .093 Boomfab Titanium Carrier and Rifle buffer w/ weights removed
4. .096 Voodoo LW Carrier Rifle Buffer
5. .096 Full Weight Carrier and Rifle buffer
6. .099 RCA LW Carrier, Young LW Carrier and Rifle buffer w/ weights removed

We port our 16″ Rifle gas barrels to .101″ to accommodate any of the configurations above.