07-29-2013, 08:47 PM
18" + RLGS with too small of a gas port will give you short-stroking. The fact that it ran with your suppressor attached says that the system is tuned for suppressor use, so if you end up opening the gas port, you might want an adjustable gas block. Also, with temps as warm as they have been, you also need to think about cold weather and how it will run then.
I always thought that an 18" RLGS made a lot of sense, and it does in 5.56 NATO, but Bill A. discoverer rather quickly that 18" Grendels with RLGS are finicky because of dwell time. 6.8 SPC is the same way. The 18" RLGS does seem to provide higher muzzle velocities though, and your chronograph readings support that suspicion I've had. Your factory Hornady average is 20fps faster than Hornady's reported velocity of 2580fps from a 24" barrel.
The cartridges that were jammed into the extension teeth are often caused by bolt over base FTFeed malf's. The carrier doesn't travel rearward enough, but the carrier face rather than the bolt, picks up a cartridge, then pinches the snot out of it between the bolt, the magazine, and the feed ramps.
Since you're getting accuracy and amazing muzzle velocity, I would think that opening the port will probably be the outcome of this trouble-shooting process. Think about the fact that a 20" Grendel with RLGS uses a .094" gas port diameter, and you know that the 18" RLGS system is going to have to be larger to get the same carrier thrust equivalent, although the dwell time will still be shorter.
For shooting pills with long bearing surfaces, your carbine is ideal, especially looking at the velocity you're getting. Let me know if you want to get rid of the barrel/bolt combo.
I always thought that an 18" RLGS made a lot of sense, and it does in 5.56 NATO, but Bill A. discoverer rather quickly that 18" Grendels with RLGS are finicky because of dwell time. 6.8 SPC is the same way. The 18" RLGS does seem to provide higher muzzle velocities though, and your chronograph readings support that suspicion I've had. Your factory Hornady average is 20fps faster than Hornady's reported velocity of 2580fps from a 24" barrel.
The cartridges that were jammed into the extension teeth are often caused by bolt over base FTFeed malf's. The carrier doesn't travel rearward enough, but the carrier face rather than the bolt, picks up a cartridge, then pinches the snot out of it between the bolt, the magazine, and the feed ramps.
Since you're getting accuracy and amazing muzzle velocity, I would think that opening the port will probably be the outcome of this trouble-shooting process. Think about the fact that a 20" Grendel with RLGS uses a .094" gas port diameter, and you know that the 18" RLGS system is going to have to be larger to get the same carrier thrust equivalent, although the dwell time will still be shorter.
For shooting pills with long bearing surfaces, your carbine is ideal, especially looking at the velocity you're getting. Let me know if you want to get rid of the barrel/bolt combo.