The 18 barrel can be purchased with mid length gas port or rifle length gas port location. The location and size of the gas port can affect reliability especially if using a suppressor. Having an adjustable gas block can be handy but normally not necessary unless you plan on using a suppressor. The 18 mid length 6.5 Grendel tend to be more finicky with a suppressor than the rifle length gas system on an 18 barrel.
I never use a suppressor and my 18 Faxon Group Buy Monster barrel with mid length gas system with standard carbine buffer and spring has been 100 % reliable. Put a suppressor on it and Im sure it would be over gassed. Some barrel manufacturers have sold 18 6.5 Grendel barrels with over sized gas ports on mid length gas barrels. Those barrels usually benefit from an adjustable gas block, adjustable gas carrier key (Rubber City Armory) or adjustable gas bolt carrier like Bootleg.
My first 6.5 Grendel was a 16 complete upper I bought with a carbine length gas system. This barrel is over gassed and I finally fixed it by using a Rubber City Armory adjustable gas carrier key. The 6.5 Grendel has a little learning curve. Generally if you step away from 223/5.56 there can be occasional issues whereas the 223/5.56 there is a longer history and knowledge base. Magazines seem to be affected by poor quality control for the 6.5 Grendel compared to 223/5.56 AR-15s.
I have two 16, one 18, one 20 and one 12 6.5 Grendel AR-15s. The only troublesome upper was the 16 upper I bought complete. The uppers Ive assembled myself have been as reliable as my 223/5.56 AR-15s. I own 33 AR-15 6.5 Grendel mags and Ive had problems with two which I fixed myself. Those two magazines caused stoppages but were quickly fixed. One ASC 25 round mag needed a feed lip adjusted. One 24 round E-Lander had rough welds on the spine which added drag to the follower. A few passes with a file fixed that mag.
I never use a suppressor and my 18 Faxon Group Buy Monster barrel with mid length gas system with standard carbine buffer and spring has been 100 % reliable. Put a suppressor on it and Im sure it would be over gassed. Some barrel manufacturers have sold 18 6.5 Grendel barrels with over sized gas ports on mid length gas barrels. Those barrels usually benefit from an adjustable gas block, adjustable gas carrier key (Rubber City Armory) or adjustable gas bolt carrier like Bootleg.
My first 6.5 Grendel was a 16 complete upper I bought with a carbine length gas system. This barrel is over gassed and I finally fixed it by using a Rubber City Armory adjustable gas carrier key. The 6.5 Grendel has a little learning curve. Generally if you step away from 223/5.56 there can be occasional issues whereas the 223/5.56 there is a longer history and knowledge base. Magazines seem to be affected by poor quality control for the 6.5 Grendel compared to 223/5.56 AR-15s.
I have two 16, one 18, one 20 and one 12 6.5 Grendel AR-15s. The only troublesome upper was the 16 upper I bought complete. The uppers Ive assembled myself have been as reliable as my 223/5.56 AR-15s. I own 33 AR-15 6.5 Grendel mags and Ive had problems with two which I fixed myself. Those two magazines caused stoppages but were quickly fixed. One ASC 25 round mag needed a feed lip adjusted. One 24 round E-Lander had rough welds on the spine which added drag to the follower. A few passes with a file fixed that mag.