04-14-2018, 03:51 PM
I’ve seen AR-15’s which would eject the fired round but the bolt/carrier doesn’t move far enough to the rear to pick up the top round of the mag to start to feed. Most times this is because of gas leakage/insufficient gas or an under powered round. In a brand new rifle it takes more gas to cycle the action. A well lubed worn in rifle generally needs less gas to cycle than a brand new rifle. One of the advantages of an adjustable gas block is you can tune the rifle as it wears in, you change ammo or use a suppressor.
One other thing to remember is that different powders have different burn rates and dwell time. I have a 16” carbine length gas system 6.5 Grendel which will short stroke on 120-123 grain bullets loaded with CFE223 powder. The rifle has functioned with all other loads but apparently the slower burn rate CFE223 doesn’t build enough pressure in the short gas system to cycle. This same load has functioned in all other 6.5 Grendel AR-15’s I tested (7 or 8 other 6.5 G AR-15’s). Solution is I just don’t use that load in that particular 6.5 Grendel AR-15.
One other thing to remember is that different powders have different burn rates and dwell time. I have a 16” carbine length gas system 6.5 Grendel which will short stroke on 120-123 grain bullets loaded with CFE223 powder. The rifle has functioned with all other loads but apparently the slower burn rate CFE223 doesn’t build enough pressure in the short gas system to cycle. This same load has functioned in all other 6.5 Grendel AR-15’s I tested (7 or 8 other 6.5 G AR-15’s). Solution is I just don’t use that load in that particular 6.5 Grendel AR-15.