Ballistic Advantage is known for using small size gas ports on their 6.5 Grendel barrels. BA assume people are going to run suppressors which is why they use smaller gas ports. There are numerous threads where people opened the gas port or sent their barrels back to BA to get the port enlarged.
Are you currently running a suppressor? If no suppressor the signs for under gassed and over gassed can be the same. Id check the extractor and if there is no damage to the hook Id remove the black O ring on the extractor stem and spring. In my opinion with a rifle length gas with no suppressor with 18 Id check the gas port size. The information I have listed for a 18 Rifle length gas system is .094 minimum. You didnt mention if your using a rifle length buffer tube or carbine length buffer tube. If your using a carbine length buffer tube Id use a carbine length spring and supplied carbine buffer (3 ounce). Id start with the adjustable gas block almost closed and fire one round with no rounds in the mag. Depending on how much if any movement you get on the bolt would determine how much more Id open the gas block.
Id try incremental changes making small adjustments and once the rifle cycled and locked the bolt back I would then try adding a round or two in the magazine. If the gas port is properly sized you shouldnt need the gas block/port wide open without a suppressor. You shouldnt need a heavy buffer with a rifle length gas 18 barrel without a suppressor. If you still cant get the barrel to function Id definitely measure the gas port. Id also inspect the ejector and spring. If the ejector is not freely moving this could create issues your experiencing.
Here is a link to the google custom search. You can look at the previous discussion on ballistic Advantage barrels with gas issues. You might gain some good information from looking at past threads.
https://cse.google.com/cse?cx=0163689474...cu1o&hl=en
Are you currently running a suppressor? If no suppressor the signs for under gassed and over gassed can be the same. Id check the extractor and if there is no damage to the hook Id remove the black O ring on the extractor stem and spring. In my opinion with a rifle length gas with no suppressor with 18 Id check the gas port size. The information I have listed for a 18 Rifle length gas system is .094 minimum. You didnt mention if your using a rifle length buffer tube or carbine length buffer tube. If your using a carbine length buffer tube Id use a carbine length spring and supplied carbine buffer (3 ounce). Id start with the adjustable gas block almost closed and fire one round with no rounds in the mag. Depending on how much if any movement you get on the bolt would determine how much more Id open the gas block.
Id try incremental changes making small adjustments and once the rifle cycled and locked the bolt back I would then try adding a round or two in the magazine. If the gas port is properly sized you shouldnt need the gas block/port wide open without a suppressor. You shouldnt need a heavy buffer with a rifle length gas 18 barrel without a suppressor. If you still cant get the barrel to function Id definitely measure the gas port. Id also inspect the ejector and spring. If the ejector is not freely moving this could create issues your experiencing.
Here is a link to the google custom search. You can look at the previous discussion on ballistic Advantage barrels with gas issues. You might gain some good information from looking at past threads.
https://cse.google.com/cse?cx=0163689474...cu1o&hl=en